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states, commonly at the middle of the bit or chip period. The transition may be between amplitude, frequency or phase states. Media Access Control (MAC) Address: The MAC address is a unique hardware address of a network interface device and is used by Layer 2 pro- tocols to address data packets to a desired destination device. MAC addresses are 48-bits long, although a 64-bit Extended Unique Identifier has been developed by the IEEE. MICHAEL (MIC): The message integrity check (MIC) is a feature of the wireless protected access (WPA) enhancement to IEEE 802.11 security, developed by the Wi-Fi Alliance as an interim improvement on WEP in advance of the IEEE 802.11i standard. Chapter Sixteen Miller Coding: Miller coding is a type of Manchester coding (q.v.) where a 1-bit is represented by a transition of some type (amplitude, frequency, phase) at the centre of the bit period and a 0-bit is represented by no tran- sition. A repeated 0-bit is represented by a transition at the start of the bit period. In modified Miller coding, each transition is replaced by a negative pulse. Modulation: Modulation is the technique used to combine a digital data stream with a transmitter's carrier signal. Modulation Index: The modulation index is defined as [A-B] / [A+B] where A and B are the maximum and minimum signal amplitudes. Multicast: A multicast message is transmitted to a subset of all stations on the network, in contrast to broadcast and unicast messages (q.v.). Multipath Interference: See Fading Multiple Input Multiple Output (MIMO): Multiple Input Multiple Output refers to wireless links with multiple transmitter and receiver antennas. Processing signals from multiple antennas can increase the available data bandwidth or reduce the average bit error rate (BER) of the link, by exploiting spatial diversity (spatial multiplexing). Network Address Translation (NAT): Network Address Translation is the replacement of a local network address with an address that can be used on an external network such as the Internet, and is perf

ormed by the gate- way device that connects the two networks. Nonce: A random number used once and then discarded, for example as the seed for an algorithm used to determine encryption or authentication keys. Omnidirectional Antenna (Omni): An omnidirectional antenna has a 360 degree beamwidth in the horizontal plane (perpendicular to the axis of a vertically mounted antenna), and is used when transmission and reception is needed in all radial directions. The gain of an omni can be increased at the expense of reducing the vertical beamwidth. Glossary Orthogonal Frequency Division Multiplexing (OFDM): OFDM is a multiplexing technique in which a data stream is split into a number of parallel streams of lower bit rate which are modulated onto a set of subcar- riers and transmitted concurrently. The characteristic of orthogonality refers to the frequency separation of the subcarriers which is chosen to reduce inter-carrier interference. Packet Binary Convolution Coding (PBCC): Packet Binary Convolution Coding is a data coding and modulation scheme developed by Texas Instruments as a proposal for the 802.11g standard. OFDM was selected in preference to PBCC as it delivers 54 Mbps compared to the 33 Mbps achievable with PBCC. Pairing: The initial step in creating a link between Bluetooth devices when a PIN is entered into both devices. Pair-wise Temporal (or Transient) Keys: Encryption keys that are derived as part of a device authentication process and used by both devices to encrypt data traffic for the duration of the connection. Personal Computer Memory Card International Association (PCMCIA): The Personal Computer Memory Card International Association was formed in 1989 to define standards for portable computer expansion cards. PCMCIA cards are now known as PC cards. Piconet: An ad-hoc collection of devices in a PAN with one device acting as a master and the others as slaves. The master device sets the clock and other link parameters such as a FHSS hopping pattern. In Bluetooth piconets, each master can connect to

7 active or up to 255 inactive (parked) slave devices. Point of Attachment (POA): A point of attachment is a generic point at which wireless device connects to a wireless network. Wi-Fi access points and WiMAX or 3GPP cellular base stations are all examples of points of attachment. Point of presence (POP): A point of presence (POP) is an access point into the Internet. An ISP or other online service provider will have one or more POPs to carry customer traffic onto the Internet. Chapter Sixteen Point to Point Transport Protocol (PPTP): A protocol that allows secure transmission of data over virtual private networks (VPN) that make use of insecure connections such as the public telephone system or the Internet. Processing Gain: Processing gain is achieved when a chipping code is used to spread a bit stream into a wider bandwidth chip stream. The pro- cessing gain in decibels is equal to 10 logio(C) where C is the length of the chipping code. Protocol: A standard set of rules, or language, for enabling network com- munication between devices. Examples of protocols include HTTP, FTP, TCP and IP. Quadrature Phase Shift Keying (QPSK): A modulation technique in which an input data symbol is represented by one of four phase states of the carrier wave. Receiver Sensitivity: The receiver sensitivity is a measure in dBm of the weakest signal that a receiver can reliably decode at a specified bit error rate (BER). Receiver sensitivity is a function of the modulation method used, since more complex schemes, such as 16- or 64-QAM, require a higher received signal strength for reliable decoding. Typically, decoding 64-QAM requires 15-20 dB higher signal strength than decoding BPSK. Request for Comments (RFC): A publication by an industry body requesting comments on a proposal relating to standards or generic solutions to a technical problem. The Network Working Group publishes some of the seminal RFCs that established the fundamentals of much of the networking and Internet technology described in this book. Some important exa

mples are; RFC 791 Internet Protocol RFC 1738 Uniform Resource Locators (URL) RFC 1945 Hypertext Transfer Protocol (HTTP 1.0) The RFC archive at www.faqs.org/rfcs is a fascinating history of the development of these key technologies. Glossary Router: A router is a network device that examines the IP address within a data packet and forwards the packet on towards its destination. The sharing of information between routers about paths to other network destinations is achieved using protocols such as Router Information Protocol (RIP), Open Shortest Path First (OSPF) and Intermediate System to Intermediate System (IS-IS). RSA public key algorithm: The RSA algorithm is named after cryptographers Rivest, Shamir and Adleman, and is used in public key cryptography to establish a public plus private key pair. The algorithm starts with two large primes, p and q, whose product n = pq. A number e is chosen that is less than n and such that e and (p-1)(q-1) have no common factor except 1. Another number d is found such that (ed - 1) is divisible by (p-1)(q-1). The public key is the pair (n, e), the private key is (n, d). The security of the RSA algorithm is based on the difficulty of factoring a product of two large prime numbers. If this could be done then the private key could be computed from the public key. Scatternet: A scatternet is the linking of multiple co-located Bluetooth piconets through the sharing of a common device. A device in a scatternet can be both a master in one piconet and a slave in another. Service Set Identifier (SSID): The SSID identifies a group of wireless devices networked through a single access point. Data packets transmitted between these devices are identified by carrying the SSID, and will be ignored by devices operating under a different SSID. Simple Network Management Protocol (SNMP): Simple Network Management Protocol is a communications protocol that enables the con- figuration and monitoring of network devices such as access points and gateways. SNMP is used to perform network management

ing of encryption keys between access points and associated wireless stations. Transport Control Protocol (TCP): TCP manages the transport of mes- sages over a network, including the fragmentation into packets, in sequence reconstruction from received packets, error checking and requests to retransmit missing packets. Tunnelling: Tunnelling creates a secure link across an unsecured network by encapsulating data packets structured according to one protocol with a wrapper defined by another protocol. Tunnelling involves three different protocols; a carrier protocol used by the network that the data is transmit- ted over (e.g. IP), an encapsulating protocol that provides the wrapper and the passenger protocol that structures the original data packet. Turbo codes: Turbo codes are error correction codes that rely on the com- putation of two independent parity checks on each data block. On decod- ing, the two check codes are used to independently verify the received data block. If the two decoders disagree on the data block an iterative exchange of information takes place until they converge on a single solution. User Datagram Protocol (UDP): UDP is a data transport protocol that performs similar functions to TCP, but does not check for the arrival of all Glossary data packets or request retransmission if any packets are missed. UDP is used in applications such as VoIP or media streaming, where recovery of missed packets is of no value and they are simply dropped. Unicast: A unicast message is transmitted to a single identified receiving station, in contrast to multicast and broadcast messages (q.v.). Unshielded Twisted Pair (UTP): Unshielded twisted pair is the most common type of cabling for wired Ethernet connections and consists of four twisted copper wire pairs, terminated with an RJ45 connector. Different cat- egories of UTP cabling are defined for different network speeds from Cat 1 for low speed (1 Mbps), Cat 5 the most common Ethernet cabling for 100 Mbps, up to Cat 7 for ultra-fast Ethernet at 10 Gbps. Ultra

Wide Band (UWB): Ultra Wide Band is defined as any transmis- sion in which the 3 dB bandwidth is 20% or more of the centre frequency, with a minimum bandwidth of 500 MHz. In the USA, the FCC defines a UWB passband from 3.1 to 10.6 GHz in which maximum transmitter power must be below -41.3 dBm/MHz. This power level is less than that permitted for unintentional emitters such as computers and other electronic devices. Voice over Internet Protocol (VoIP): Voice over Internet Protocol refers to the transmission of voice data over the Internet using the UDP transport protocol. Virtual LAN (VLAN): A virtual LAN is a subset of client stations in a LAN or WLAN that is defined using software in order to be able to isolate traffic in the VLAN from the wider LAN. For example this may be because traffic in the VLAN is more susceptible to attack (e.g. VoIP phones) and needs to be treated as "untrusted" to assure the security of the rest of the LAN. Virtual Private Network (VPN): A Virtual Private Network is formed when a remote device connects to a private network via a public network such as the Internet. A tunnelling protocol such as IPSec, L2TP or PPTP ensures privacy by encrypting data transferred over the public network. Wired Equivalent Privacy (WEP): A security feature of the 802.11 stan- dard that was intended to provide security equivalent to that of a wired LAN. Chapter Sixteen Encryption vulnerabilities led to WEP being superseded by WPA and by 802.11i security mechanisms. Wireless Ethernet Compatibility Alliance (WECA): Original industry sponsors of the Wi-Fi standard, now re-branded as the Wi-Fi Alliance. The Wi-Fi logo gives a guarantee of interoperability of 802.11 based wireless networking devices. Wi-Fi Protected Access (WPA): An enhanced version of IEEE 802.11 security, developed by the Wi-Fi Alliance as a precursor to the IEEE 802.11i standard, which provides stronger encryption and manages the dis- tribution of encryption keys. WPA also provides user authentication and message integrity checking (MICHAEL).

Wireless Personal Area Network (WPAN): A network for communica- tion and inter-connection of devices within a personal operating space, with emphasis on short-range, low power and low cost. Wireless Internet Service Provider (WISP): A public Internet service provider using wireless network connections to subscribers. Wireless Local Area Network (WLAN): A wireless network that uses licensed or unlicensed radio frequencies such as the 2.4 or 5 GHz ISM bands to connect wireless enabled computers or other devices in a local area extending typically over 10-100 metres. X-10: A power line based home automation technology, primarily used for lighting control. ZigBee: A wireless networking technology based on the IEEE 802.15.4 PHY and MAC standard, and aimed at short range, very low power and low data rate monitoring and control applications. Index 2B1Q, 29-30 802.11a, 150, 345 3GPP, 349 802.11h compliance, 160 4B/5B, 27 HiperLAN/2 similarity, 171 4-PPM, 283 key features, 140 4-way handshake modulation and coding schemes, 172 BSS transitions, 164 OFDM, 92 RSN key management, 222 operating range, 180 16-QAM, 102 PHY layer, 150 Gray coding, 102-3 QAM modulation, 102 802.11a OFDM, 151 QPSK modulation, 100 64-QAM, 102 ratification, 139, 150 802.11a OFDM, 151 802.11b, 46 802.1x, 212 channel allocation, 186-88 authentication framework, 214 channel availability at 2.4 GHz, 154 EAPoL transport, 217 frequency hopping parameters, 84 802.2, 20 high rate DSSS, 149 802.3, 26 key features, 140 802.5, 24 modulation and coding schemes, 172 802.11 modulation methods, 153 basic service set 142 operating range, 180 CSMA/CA, 145 PHY layer, 152 enhancements, 156 QPSK modulation, 100 extended service set, 143 ratification, 139 logical architecture, 141 spread spectrum techniques, 80, 83 logical link control, 144 802.11d media access control, 144 key features, 140 MAC coordination functions, 145 802.11e, 157-60 network components, 142 ESS mesh QoS, 168 origins, 139 key features, 140 PHY layer, 148 voice traffic, 201 resources, 367 WiMedia MAC,

267 standards suite, 140 802.11f VoIP enhancements, 202 key features, 140 Index 802.11g 802.15, 253 (Continued) key features, 140 802.15.4a, 80, 273, 280 modulation and coding schemes, 172 impulse radio, 121 OFDM, 92 MAC security services, 305 operating range, 180 radio, 100 PHY layer, 154 resources, 365 QAM modulation, 102 standards and task groups, 254 ratification, 139, 154 standing committee SCwgn, 293 802.11h, 160, 345 see also ZigBee key features, 140 802.16, 309-19, 328 spectrum management, 151 802.16-2004, 310, 321 802.11i, 48, 209, 219-20 802.16a, 309 key features, 140 key parameters, 313 RSN security protocol, 227 802.16e, 66, 316-18 troubleshooting, 245 802.16f/g, 319 WPA interim measure, 212 frame structure, 311 802.11j key parameters, 311 key features, 140 management connections, 314 802.11k, 143, 162 optional air interfaces, 313 key features, 140 PHY layer, 310 transmit power control, 119, 163 resources, 369 802.11n, 46, 125, 165 standards suite, 310 Enhanced Wireless Consortium, 165 802.21 gigabit wireless LAN, 350 media independent key features, 140 handover, 165, 348 OFDM modulation, 167 802.22, 356-58 802.11p key features, 140 802.11r, 162 Access categories see Traffic classes key features, 140 Access point fast BSS transitions, 164 array, 43, 52 voice services, 201 BSS example, 142 802.11s, 45, 167-69 channel allocation, 186-88 key features, 140 channel switching, 161 resources, 368 configuration, 189, 191-94 802.11T, 248 automatic, 196 key features, 140 fat, 46, 196 802.11u functionality, 46 key features, 140 link margin report, 161 802.11v location, 183 key features, 140 pilot testing, 191 802.11w rogue key features, 140 detection, 189, 235-36 802.15, 253 hacking threat, 207 802.15.1 thin, 47 origins, 254 transitions between, 162, 201 resources, 364 transmit power control, 161 see also Bluetooth wireless LAN controller, 48 Index Adaptive burst profiling Antenna (Continued) 802.16 radio link control, 315 wireless MAN, 64-5 glossary, 381 wireless PAN, 62 Adaptive frequency hopping glossary, 38

1 radiation pattern, 108 Adaptive rate selection see Dynamic rate AntHocNet, 43, 346-47 shifting APIPA, 15 Address resolution protocol, 13 Apple Computer Inc. 1394 ARP, 32 iLink, 30 ARP cache, 16 Application layer Ad-hoc mode described, 10 IBSS operation, 142 e-mail example, 11 dynamic frequency selection, 162 MSDU and, 22 topology, 143 Arbitrary inter-frame spacing, 157 Advanced encryption standard, 212, 225 ARIB, 73-5 CCMP encryption, 228-29 802.11b channels, 153 SSL support, 237 ARP spoofing, 207 WPA2 implementation, 220 Association AIFS see Arbitrary inter-frame spacing 802.11 networks, 147 ALOHANET, 1 MAC distribution system service, 149 Alternating wireless medium access, 249 TPC in association frame, 161 Ambient noise, 118 Asynchronous Antenna connectionless links, 259 adaptive beam, 57 IrDA SIR format, 282 MIMO compared, 59 WiMedia MAC, 269 beam-forming see adaptive beam Authenticator, 214 dipole, 107 Authentication radiation pattern, 107-8 802.11 networks, 147 directed beam, 58 802.1x, 164, 212 directional, 107 Bluetooth security, 301 radiation pattern, 107-8 EAP, 216 wireless MAN application, 327 MAC station service, 148 diversity, 57 server, 213-19 diversity gain, 166 wireless LAN security, 208 gain, 107 wireless robust authenticated protocol, 227 helical, 56 wireless USB security, 304 impedance, 108 Authorisation omnidirectional, 55 Bluetooth security, 301 wireless MAN application, 327 Auto-correlation parabolic, 331 chipping codes, 82 patch, 331 plasma, 59 polarisation, 55 Backhaul sector, 41, 52, 55 glossary, 382 wireless MAN application, 327 MAN provisioning, 332-33 smart, 56, 94 Back-off period 802.16a support, 312 in CSMA/CA, 25, 145 switched beam, 57 in CSMA/CD, 24 Index Back-off period (Continued) Bluetooth (Continued) mixed mode operation, 155 enhanced data rate, 101 randomised, 145 devices, 60, 255 traffic class dependence, 157, 159 discovery, 259 Bandwidth features, 61 dynamic control, 119 security levels, 301 glossary, 382 frequency hopping spread granting in 802.16, 314-16 spectrum, 85 Ban

dwidth efficiency see Spectral efficiency glossary, 382 Barker codes, 80-3, 110 host controller interface, 260 802.11b PHY, 152-53 jamming, 207 glossary, 382 L2CAP, 261 Base station, 327 link manager protocol, 260 Baseband master device, 40 Bluetooth, 259 maximum transmission unit, 261 glossary, 382 packet types, 259 Basic service set pairing, 262 ad-hoc mode, 142 power classes, 258 beacon frames, 142 profiles, 255-56 benefits, 143 protocol stack, 257 BSSID, 142 radio, 258 infrastructure mode, 142 DPSK modulation, 101, 258 transitions, 163-64 Gaussian FSK, 102, 258 Beacon frames, 142 resources, 364 time synchronisation, 147 RFCOMM, 261 quiet period specification, 161 security, 300-03 SSID broadcast, 231 services Beacon reports discovery, 262 802.11k, 163 security levels, 301 Beam pattern special interest group, 255, 265 infra-red, 131-32 standard data rate, 102 WLAN antennas, 107-8 usage examples, 263 Binary phase shift keying, 98 VoIP connection, 349 802.11a, 151 vulnerabilities, 302 802.11b, 153 Bridging, 53 glossary, 382 WLAN point-to-point, 189 Bit error rate, 96, 109, 112, 129 British Telecom, 349 data rate dependence, 153 Broadcast, 383 WLAN layout, 188 monitoring, 207 Block cipher Broadband wireless access, 309 cipher block chaining, 227 BSS see Basic service set counter mode operation, 226 BSSID, 142 electronic code book, 226 Business planning offset code book, 227 MAN implementation, 323, 332 Bluesnarfing, 302 Bluetooth application profiles, 256 Cash flow projection, 336-37 connection states, 260 Change control, 197 Index Channel allocation Control frames 802.11b access points, 186-88 CTS/ACK, 146 Channel bonding DTR/DSR, 261 802.11g enhancement, 156 mixed mode operation, 155 Channel state information RTS/CTS, 155 MIMO radio, 125 Bluetooth RFCOMM, 261 802.1 11k reports, 163-64 Cover ge holes, Channel switching WLAN site survey, 184 access point initiation, 161 Cross-correlation Chipping codes, 80, 82 chipping codes, 82 auto-correlation, 82 Cryptoanalytic attacks, 207 direct sequence UWB radio, 122 CSMA/C

A, 25, 145 glossary, 383 glossary, 383 length versus processing gain, 153 CSMA/CD, 23 multi-channel CDMA, 353 glossary, 383 orthogonality, 82, 353 timing, 24 Ciphers Customer mapping, 334 block, 225 Customer premises equipment, 331 cipher block chaining, 227 installation, 332 counter mode operation, 226 Cyclic redundancy check electronic code book, 226 glossary, 384 offset code book, 227 WEP message integrity, 210, 213 Rijndael, 225 stream, 225 Code division multiple access, 94 Data encryption standard, 226 Coding rate Data link layer 802.11a PHY, 151-52 described, 10 802.11g PHY, 154 e-mail example, 11 802.11n mechanisms, 166 technologies, 20 defined, 151 ISDN, 30 Coexistence Data rate alternating wireless medium access, 249 802.11/a/b/g comparison, 157 Bluetooth and 802.11, 247 effective, 156, 165 deterministic frequency nulling, 249 headline versus effective, 156 wireless LAN attribute, 178 versus operating range, 2 wireless PAN attribute, 298 Data transfer Cognitive radio, 355 asynchronous, 32 resources, 370 see also Asynchronous Communication services isochronous, 32 connection oriented, 21, 314, 383 see also Isochronous connectionless, 21 Complementary code keying, 82 defined, 106 802.11b PHY, 152-53 glossary, 384 glossary, 383 DCF see Distributed Connection oriented, 21, 383 coordination function 802.16 MAC, 314 Deauthentication Contention period, 25 MAC station service, 148 Contention free period, 147 Default gateway, 14 Index Delay spread Dual carrier modulation, 104, 123 glossary, 384 Dual mode mobile WiMAX, 316 VoIP handsets, 202 multipath, 114 Dynamic rate shifting voice services, 201 802.11b PHY, 152 Denial of service, 206 Dynamic frequency selection Detector sensitivity 802.11h, 160-62 infra-red, 132 ad-hoc mode, 162 wavelength dependence, 133 glossary, 385 Deterministic frequency nulling, 249 DFS see Dynamic frequency selection Differential phase shift keying, 100 EAP see Extensible authentication 802.11b DPSK, 152 protocol glossary, 384 ECMA 340, 287 DIFS see Distributed inter-frame spacing field

strength specification, 288 Digital signatures modulation and coding, 289 PKI certificates, 219 Effective data rate SSL certificates, 239 Bluetooth, 255 voice service security, 203 wireless LAN attribute, 178 Direct sequence spread spectrum, 83-4 wireless PAN attribute, 297 glossary, 385 Effective isotropic radiated power interference with FHSS, 248 802.11a limits, 150 ZigBee radio, 276 defined, 107 Direct sequence UWB radio, 121 FCC and ETSI limits, 73-4 Directed beaconing glossary, 385 wireless USB devices, 270 wireless MAN set-up, 326 Disassociation Electromagnetic spectrum MAC distribution system service, 149 see Spectrum Distributed coordination function, 145 Encoding 802.11e enhancements, 157 2B1Q, 29-30 timing, 146 4B/5B, 27-28 Distributed inter-frame spacing, 145 MLT-3, 28 Distributed reservation channel access, 168 Manchester, 28 Distributed reservation protocol NRZI, 33 WiMedia MAC, 268 noise immunity and, 34 Distribution system E-mail ESS operation, 144 OSI example, 11 MAC services, 147, 149 Emitter power density, 131 mesh networks, 167 Encryption wired, 143 cipher block chaining, 220 wireless, 167 counter mode, 226 Diversity electronic code book, 226 frequency, 318 stream ciphers, 225 glossary, 385 Enhanced DCF, 145 spatial, 59 timing, 158-59 Diversity gain, 166 Enhanced Wireless Dual band radios Consortium, 165 WLAN application, 183 Ericson Mobile Communications, 254 Index Error correction FireWire, 26 802.16e enhancements, 317 CSR architecture cyclic redundancy check, 384, range, 31 210, 213 resources, 366 forward error correction, 386 topology, 31 low density parity check, 351 wireless 1394, 123, 272 ESS see Extended service set Frame bursting see Packet bursting Ethernet, 1, 26 Free space loss, 112-14 address, 22 Frequency diversity, 318 collision detection, 145 Frequency division duplexing, 88-89 CSMA/CD and, 23 802.16, 311 fast, 27 Frequency division multiple ETSI, 73-75 access, 88-89 802.11b channels, 153 Frequency hopping spread Bluetooth RFCOMM adaptation, 261 spectrum, 84-85 DECT and HomeRF,

170 Bluetooth hopping patterns, 262 HIPERMAN, 319 French regulations, 85 Evil twin intercept, 207 glossary, 387 Exposed station, 76 interference, 247-48 Extended service set multi-band OFDM, 123 defined, 143 Frequency reuse, 355 roaming between, 144 glossary, 386 Extended unique identifier polarisation based, 355 1394 ARP and, 32 Frequency shift keying, 101 glossary, 386 Gaussian, 102 Extensible authentication Freshness check protocol, 215 ZigBee security, 305 4-way handshake, 223 Fresnel zone theory, 114 EAPoL, 216 glossary, 387 EAP types, 217 WMAN site survey, 324 key hierarchy, 222 Gaussian frequency shift keying, 102 Fade margin, 116-17 Gateway, 387 Fading Gigabit wireless LAN, 350 glossary, 386 usage scenarios, 351 Fast Fourier transform, 92 Grant per connection, 316 multi-channel CDMA, 353 Gray coding, 102-103 FCC, 73-5, 150 Guard interval, 92 802.11b channels, 153 802.11n, 166 spectrum policy review, 356 multi-channel CDMA, 353 television spectrum reuse, 356-58 Guard tones, 123 Financial plan, 336 profitability analysis, 337 Firewall Hacking threats, 205 glossary, 386 Harris Semiconductor, 82 voice service security, 239 HCF see Hybrid coordination function wireless hotspot security, 238 HCF controlled channel access, 159 Index Hidden station, 76 Interference (Continued) 802.111 reports, 163-64 dynamic rate shifting, 152 wireless USB awareness, 270 DSSS and FHSS, 248 HiperLAN/2, 171-73, 183 mitigation techniques, 118 resources, 369 multipath, 58, 91, 114 HIPERMAN, 319 packet fragmentation strategy, 155 key parameters, 320 site survey, 184 Home area network, 274 transmit power control, 161 Home automation, 61 wireless LAN attribute, 178 Home RF, 87, 170, 183 wireless PAN attribute, 298 shared wireless access protocol, 170 ZigBee, 279 Inter-frame spacing active, 38 traffic class dependence, 159 passive, 39 International Telecommunications Union, 73 switching, 39 spectrum harmonisation, 151 glossary, 394 Internet Engineering Task Force, 49, 51 Hybrid coordination function, 158 Internet point-of-presence, 332

glossary, 391 Interoperability IBSS see Independent basic service set 802.11b and 802.11g, 139, 155 ICMP, 17 Bluetooth and UWB, 265 IrDA, 283 OSI model and, 12 spectrum sharing, 357 IEEE 1394 see FireWire wireless PAN user requirement, 297 iLink see FireWire Inter-packet gap, 27 Impedance matching, 108 Inter-symbol interference, 91 Impulse radio Intrusion detection, 235-37 pulse position modulation, 104 Inverse fast Fourier transform UWB radio, 121 multi-channel CDMA, 353 ZigBee candidate PHY layer, 86 Inverse square law, 131 Independent basic service set, 142 IP address, 13 topology, 143 access point configuration, 193 Inductive coupling glossary, 388 load modulation, 128 IANA, 15 NFC devices, 127 IP 1394, 32 Industry Canada, 73-4 IP v6, 15 Infrastructure mode IP v7, 16 BSS operation, 142 private, 15, 18-9 glossary, 387 IrBurst, 296 topology, 143 Initialisation vector device alignment, 281 glossary, 387 LAN access, 286 WEP encryption, 209 link distance, 282 Insertion attack minimum emitter power, 132 hacking threat, 207 origins, 280 Instrument, Scientific and Medical, 71 physical layer, 131, 282 spectrum allocation, 72 protocol stack, 282 Interference optional, 284 802.11h extensions, 160 pulse position modulation, 104 Index IrDA (Continued) Low density parity check, 351-53 resources, 366 glossary, 389 security, 305 Lucent Technologies, 82 ISDN, 26, 29 LWAPP, 49 ISM see Instrument, Scientific and Medical functions, 51 Isochronous glossary, 388 WiMedia MAC, 268-69, 271 MAC see Media access control ITU see International Telecommunications MAN see Metropolitan area network Union Manchester coding glossary, 389 NFC coding, 289-90 Jamming MANET see Mesh networks hacking threat, 207 Man-in-the-middle attack, 207 Jitter Magnetic field strength, 288 glossary, 387 Marketing plan, 333 voice services, 201 Massachusetts Institute of Technology, 235 MBOA Alliance, 123 Kerberos, 235-36 MC-CDMA, 2 Media access control, 21 address, 20, 22 Last mile broadband access, 309 filtering, 234 Latency alternating wireless, 249 glossary,

388 contention based, 145 Leasing agreements, 338 ZigBee, 276 Light emitting diode coordination functions, 145 emitter power density, 131 CSMA/CA, 25, 276 polar diagram, 132 CSMA/CD, 23 Line-of-sight data link layer technology, 20 glossary, 388 distribution system services, 147 Link budget, 116, 129 efficiency access point report, 161 defined, 167 ambient noise environment, 118 gigabit wireless LAN, 351 fade margin, 116-17 TDMA versus CSMA/CA, 171 wireless MAN set-up, 326, 339 frame Link distance four address format, 168 infra-red, 133 structure, 22-3 Link margin see Link budget, fade margin glossary, 389 Link quality indicator, 119 header, 229 Linux, 35 protocol data unit Load modulation, 128, 289 encryption, 228-29 Location based services, 272 service access point, 53 Logial architecture, 9 glossary, 389 Logical link control, 20 service data unit, 21-22 Losses services, 144 cables and connectors, 108 station services, 147-48 free space loss, 112-14 wireless, 144 path loss, 161 WiMedia MAC media access slots, 268 Index Media access control (Continued) MIMO, 2, 43, 59, 124 wired networks, 22 glossary, 390 token, 24 space division multiplexing, 124 wireless networks, 25 Minimum threshold irradiance, 132-33 Media independent handover, 347-50 MISO, 125-26 Media reservations Mixed mode operation pre-allocation in 802.11r, 165 802.11b and 802.11g, 155 Mesh coordination function, 168 throughput impact, 155 Mesh networks, 43 Mobility distributed control, 43 distribution system, 144 implementation considerations, 279 wireless PAN user requirement, 296 metropolitan area, 321 Modulation, 95 resources, 368 4-PPM, 283 routing, 43, 345-46 802.11a OFDM methods, 151 ant inspired, 346-47 802.11n mechanisms, 166 security, 168 802.11n OFDM methods, 167 throughput, 44 802.16, 312 Message integrity check, 212, 389 adaptive burst control, 315 wireless LAN security measure, 208 binary phase shift keying, 98 wireless robust authenticated bit error rate, 110 protocol, 227 differential phase shift keying, 100 WEP, 210 dual carrier, 104,

Noise floor collision detection, 290 graphical display, 185 devices, 126 WMAN survey, 325 modulation methods, 289 Noise power density, 109 origins, 287 Noise and interference survey PHY layer, 288 WLAN site survey, 184 protocol stack, 289 Nonce resources, 367 CBC-MAC, 227 usage models, 291 glossary, 390 NetStumbler, 246 key generation, 222 Network adapter Novell Netware, 35 MAC address, 22 Null tones, 123 See also Network interface car Network address translation, 18 glossary, 390 OBEX, 281 static and dynamic, 19 IrOBEX, 285 static NAT table, 18 OFDM see Orthogonal frequency division Network architecture multiplexing logical, 9 OFDMA physical, 37-67 scalable, 316 Network bridging see Bridging Offset QPSK modulation, 100, 276 Network capacity Operating mode bandwidth requirements, 180 access point configuration, 193-94 comparison for WLAN Operating procedures technologies, 181 wireless MAN, 336 voice calls, 199-200 Operating range WLAN attribute, 178 factors influencing in WLANs, 180, 182 Network ID indoor versus PHY data rate, 182 determining, 14 versus data rate, 2 Network interface card wireless PAN attribute, 298 configuration, 194 Operating system disabling, 238 considerations, 34 wireless, 45 see also Network operating system Network layer Operations described, 10 customer helpline, 339 e-mail example, 11 financial, 340 ISDN and, 30 leasing agreement, 338 technologies, 13 performance monitoring, 197-98 Network management, 196 subscriber agreement, 338 Network operating system wireless LAN, 197 configuration, 191, 195 wireless MAN, 335 considerations, 34 operating cost elements, 336 Network performance monitoring, 197 start-up phase, 337 Index Orthogonal frequency division Personal operating space, 253 multiplexing, 2, 89, 151 Phase constellation, 99 802.11a, 151 frequency hopping, 123 802.11g, 154 Gray coding, 102-3 enhanced channel bandwidths, 165 multi-band UWB radio, 122 glossary, 391 Phase shift keying, 98 pilot tones, 92 Photodiode tone orthogonality, 90 minimum threshold irradiance, 132-33 transciever

block diagram, 93 wavelength dependence, 133 Orthogonality Physical layer multiple access codes, 95 described, 10 chipping codes, 82, 353 infra-red, 149 OFDM tones, 90 IrDA, 131 OSI model, 9-13 technologies, 25 maximum data rate and, 26 wired networks, 26 Packet binary convolution coding wireless networks, 34-5 802.11b optional modulation, 153 PLCP, 25 glossary, 391 PMD sublayer, 26 Packet bursting, 155 Physical layout Packet delay designing for WLAN, 185-89 voice services, 201 factors influencing, 186-87 Packet error rate, 109 planning tools, 187 payload size dependency, 119 provisional, 185 Packet fragmentation, 155 testing for WLAN, 183 Pairing wireless switches, 189 glossary, 391 Physical medium, 26 Pairwise temporal keys copper cable, 31 glossary, 391 glossary, 394 hierarchy, 222 optical fibre, 31 PAN see Personal Area Network radio transmission, 75 Passphrase, 209 twisted pair (UTP), 27-8 Bluetooth device pairing, 262 Piconet, 255, 262 changing default, 232 Pilot testing wireless USB security, 304 voice services, 202 Password authentication protocol, 216 wireless LAN, 176, 190 Path loss aspects, 191 access point estimate, 161 wireless PAN, 300 PBCC see Packet binary Pilot tones, 92, 123 convolution coding 802.11 PHY, 151 PCF see Point coordination function 802.11g PHY, 154 Peer-to-peer mode see Ad-hoc mode PKI see Public key infrastructure Penetration Point coordination function, 145-46 reduced at 5 GHz, 152 Inter-frame spacing, 147 see also Signal attenuation quality of service, 147 Personal Area Network Polarisation, 55-56 devices, 60 WMAN site survey, 325 rate versus range, 292 gigabit WLAN frequency reuse, 355 Index Port address translation, 19 RADIUS PAT table, 20 authentication server, 215-18 Power density, 81 EAP over RADIUS, 215 infra-red, 130 RC4 cipher, 207, 209-10, 225 Power efficiency, 96 weakness in WEP implementation, 211 Presentation layer secure socket layer support, 237 described, 10 Reassociation security see SSL MAC distribution system Print server, 53 service, 149 Probe frame TPC in asso

ciation frame, 161 802.11 association, 147 Received signal strength indicator, 119 DFS specification, 161 Bluetooth class 1 devices, 258 Processing gain, 109 roaming decisions, 163 packet binary convolution coding, 153 WLAN layout, 188 glossary, 392 Receiver sensitivity, 108 Profitability analysis, 337 defined, 111 Protocols glossary, 392 installing, 195 receiver noise figure, 110 Pseudo-noise code, 80-1, 94, 121 receiver noise floor, 108, 110-11 Public key infrastructure, 219 defined, 111 secure socket layer, 237 Reflection coefficient Pulse amplitude modulation, 29, infra-red, 134 86, 121-22 Replay attack, 207 Pulse position modulation, 86, 104 Request for Comments infra-red PHY, 149 glossary, 392 Pulse shape modulation, 105,122 RFC 1918, 15 RFID, 126, 287 RF propagation Quadrature phase shift keying, 99 local environmental conditions, 186 802.11a OFDM, 151 transmitter power, 106 802.16, 312 RF spectrum, 71 glossary, 392 regulation, 73 Quality of service unlicenced use, 74 802.11e, 157 Rijndael cipher, 225 802.16, 314 Roaming Bluetooth, 261 802.11k, 162 continuous through transitions, 165 algorithm, 163 Enhanced DCF, 158 alternative access points, 144 VoIP services, 201 roaming decisions, 163 wireless LAN attribute, 178 transition times, 201 wireless PAN attribute, 298 WLAN scenarios, 162 voice services, 201 Robust security network, 220 Radian sphere AES-CCMP, 228 defined, 126 authentication, 221 Radiant intensity information element content, 221 infra-red, 130-131 key management, 222 Radio resource measurements, 162 parameter negotiation, 221 Index Robust security network (Continued) Service access points wireless robust authenticated protocol, 227 data rate at, 156 Routing LLC SAP, 21 ant inspired, 346-47 MAC SAP, 21 bandwidth impact, 345 Session highjacking, 207 distribution system, 144 Session layer dynamic, 43 described, 10 glossary, 385 Shared keys glossary, 393 changing default, 232 MANETS, 18 Shared wireless access protocol, 170 mesh networks, 168-69, 345 Short inter-frame spacing, 146 RIP, 17 DFS chann

el switch router table, 16, 275 announcement, 161-62 stochastic, 346 Side channel attacks, 208 transitions Siemens AG, 355 heterogeneous, 348 SIFS see Short inter-frame spacing homogeneous, 347 Signal attenuation RSA algorithm, 237 building materials, 116 glossary, 393 indoors, 115 RSN see Robust security network Signal strength survey RSSI see Received signal results display, 186 strength indicator WLAN survey aspects, 185 Signal-to-interference ratio, 188 Signal-to-noise ratio, 109-12 Scalable OFDMA, 316-18 data rate dependence, 153 Scatternet, 255, 262 defined, 109 glossary, 393 WLAN layout, 188 Secure Socket Layer, SIMO, 125 presentation layer security, 11, 237-39 SISO, 125 Security Site report access point configuration, 193-94 802. 11k report, 163-64 Bluetooth, 300-303 Site survey denial of service attack, 202, 206 fade margin, 116 IrDA, 305 Fresnel zone, 324 MAC address filtering, 234 objectives, 183 mesh networks, 168-69 simulation, 324 troubleshooting, 247 subscriber location, 325, 339 wireless hotspot, 236 troubleshooting, 246-47 wireless LAN Slot time, 145 practical measures, 230-36 Smart antennas, 56, 94 security attribute, 178 802.16 support, 312 security measures, 208 wireless PAN, 300 glossary, 393 wireless switch features, 196 performance data collection, 197 wireless USB, 303-4 WLAN security, 236 voice services, 202, 239 Software defined radio, 355 ZigBee, 304-5 Solid angle SEEMesh, 45, 168 defined, 130 Serial Ir link, 281 Space division multiple access, 94 Index Space division multiplexing, 124 Switch Space time block coding, 126 wireless LAN switch, 41 Spam over internet telephony, 203 features, 50 Spatial diversity, 59 LWAPP, 49 Spatial location, 61, 272 see also Hub, switching Spatial reuse, 169 Synchronous Spectral efficiency, 83, 96, 102, 111 connection oriented links, 259 gigabit wireless LAN, 351 glossary, 394 glossary, 393 IrDA FIR, 283 Spectral shaping links, interference, 248 multi-band OFDM, 123 Spectrum electromagnetic, 129 Technical planning radio frequency, 71 MAN implementation, 3

23 FCC allocation, 72 Technical requirements map for spectrum sharing, 358 wireless LAN sensing for vertical sharing, 357 comparison of technologies, 181 Spectrum agile radio, 74, 356-58 establishing, 179 see also Cognitive radio wireless PAN Spectrum analyser comparison of technologies, 299 WMAN site survey, 325 establishing, 297 Spread spectrum, 76-87 Temporal keys integrity protocol, 212 benefits, 86-7 glossary, 394 chirp, 121 key mixing, 214 direct sequence, 78, 83-4 RSN key hierarchy, 223 frequency hopping, 78, 84-5 WPA feature, 212 glossary, 394 Texas Instruments, 153 hacking threats, 205 Thermal noise floor, 110 hybrid, 79-80 Time division multiple access, 87 pulsed FM, 79 802.16, 311 time hopping, 78 alternating wireless medium access, 249 types, 77 HiperLAN/2, 171 SSID, 51 IrLAP, 284 access point configuration, 193-94 MAC efficiency, 171 broadcast, 193 ZigBee, 276 disabling broadcast, 231 Time division multiplexing glossary, 393 802.16, 310 probe frame, 147 Bluetooth baseband, 259 Standards Time-frequency codes, 123 IEEE 1394, 31 wireless USB radio, 267 OSI model, 9 Time hopping spread spectrum, 85-6 proprietary extensions, 155 Topology Steradian, 130 ad-hoc mode, 143 Stigmergy, 346 bus, 38 Stress testing daisy chain, 31, 33, 39 voice services, 202 IBSS, 143 Subchanelization, 316, 318 infrastructure mode, 143 Subnet mask, 14, 17 ring, 37 Supplicant, 214 star, 37 Index Topology (Continued) Ultra Wideband (Continued) switched, 42 glossary, 394 wireless networks, 40 wireless USB radio, 265 tree, 31, 33, 53 wireless USB MBOA bands ZigBee supported, 275 Unicast, 395, 220 Traffic classes U-NII 802.11e, 157 802.11a OFDM PHY, 150 described, 160 University of Essex, 355 queues, 158 UNIX, 35 voice traffic, 201 Uptake curves, 334 Transitions USB, 26, 32 heterogeneous, 348 pipes, 33 homogeneous, 347 topology, 33 Transition security network, 222 wireless USB, 123 Transmit opportunity, 159 User requirements spectrum sharing, 358 wireless LAN, 175 Transmitter power, 106 considerations, 177 access point configuration, 1

93 establishing, 176 automatic adjustment, 189 wireless PAN FCC specified maximum, 107 considerations, 296-97 RA specified maximum, 107 establishing, 295 transmit power control, 119 UWB see Ultra wideband 802.11h, 160 802.16 radio link control, 315 Bluetooth class 1 devices, 258 Virtual LAN Transport Control Protocol glossary, 395 e-mail example, 11 voice service security, 239 Transport layer Voice over wireless, 157 described, 10 802.1 11r support, 164 Troubleshooting bandwidth requirements, 199 connectivity, 242, 245 case study, 199 performance, 242, 246 security, 239 problem identification, 242 solution strategies, 244 glossary, 395 wireless LAN, 241 voice service security, 239 wireless LAN analysers, 243-46, 249 wireless hotspot security, 238 Tunnelling glossary, 394 TLS tunnel, 219 Walsh/Hadamard transform, 83, 95 Turbo codes, 351-53 code division multiple access, 353 glossary, 394 Walsh codes, 95 War chalking symbols, 206 Ultra fast Ir, 286 War driving, 205 Ultra wideband, 2, 119-24 Wavelength, 71, 112 EIRP limits, 120 infra-red, 129 FCC definition, 120 Wavenumber FCC spectrum allocation, 73, 120 defined, 129 Index WDS see Distribution system, wireless Wireless robust authenticated WECA see Wi-Fi Alliance protocol, 227 WEP see Wired equivalent privacy Wireless switch WiBro, 66, 320 automatic WLAN configuration, 196 key parameters, 321 layout planning, 189 Wi-Fi see 802.11 Wireless USB Wi-Fi Alliance, 1, 220 channel creation using DRP, 269 glossary, 396 design objectives, 266 WMM adoption, 159 devices, 270-71 Wi-Fi multimedia, 159, 201 MBOA bands, 268 access category descriptions, 160 origins, 265 voice traffic, 201 protocol stack, 266 Wi-Fi protected access, 48, 169, 209 radio, 267 glossary, 396 resources, 365 TKIP, 212 security, 303-4 WPA2, 219 WMM see Wi-Fi multimedia compared, 220 Workgroups WIGWAM see Gigabit wireless LAN operating system configuration, 195 WiMAX, 40, 309-19 WPA see Wi-Fi protected access forum, 319 mobile, 316 resources, 369 see also 802.16 glossary, 396 WiMedia MAC, 267-68 distributed

reservation protocol, 268 media access slots, 268 ZigBee, 40, 273 superframe structure, 268 2.0 specification, 280 WiMedia-MBOA Alliance, 266 802.15.4 radio, 100 WiMesh Alliance, 45, 168 applications, 278 logical architecture, 169 devices, 61, 63, 273, 278 quality of service, 169 features, 62 Windows general operating framework, 275 network operating system, 34 glossary, 396 winipcfg utility, 22 interference, 279 Wired equivalent privacy, 48, 169 mesh implementation considerations, 279 cryptographic weakness, 209, 211 optional spread spectrum encryption key length, 209 techniques, 80 encryption process, 211 O-QPSK modulation, 100 glossary, 395 origins, 273 key management, 213 PHY layer, 275 key stream generation, 210 protocol stack, 274 passphrase, 209 pulse modulation, 105 war chalking symbol, 206 resources, 365 Wireless distribution system see Distribution security, 304-5 system, wireless superframe structure, 277 Wireless hotspots topologies, 275 security, 236-39 ZigBee Alliance, 273, 280 Wireless regional area networks, 356 This page intentionally left blank Telecom Handbook Understanding Business Telecommunications Systems & Services Edition JANE LAINO 4TH EDITION The Telecom Handbook Understanding Telephone Systems & Services by JANE LAINO CRC Press Taylor & Francis Group Boca Raton London New York CRC Press is an imprint of the Taylor & Francis Group, an informa business CRC Press Taylor & Francis Group 6000 Broken Sound Parkway NW, Suite 300 Boca Raton, FL 33487-2742 First issued in hardback 2017 © 2002 Jane Laino CRC Press is an imprint of Taylor & Francis Group, an Informa business No claim to original U.S. Government works ISBN 13: 978-1-138-41245-3 (hbk) ISBN 13: 978-1-57820-071-9 (pbk) This book contains information obtained from authentic and highly regarded sources. Reason- able efforts have been made to publish reliable data and information, but the author and publisher cannot assume responsibility for the validity of all materials or the consequences of their use. The authors and publishers have

attempted to trace the copyright holders of all material reproduced in this publication and apologize to copyright holders if permission to publish in this form has not been obtained. If any copyright material has not been acknowledged please write and let us know SO we may rectify in any future reprint. Except as permitted under U.S. Copyright Law, no part of this book may be reprinted, reproduced, transmitted, or utilized in any form by any electronic, mechanical, or other means, now known or hereafter invented, including photocopying, microfilming, and recording, or in any information storage or retrieval system, without written permission from the publishers. Trademark Notice: Product or corporate names may be trademarks or registered trademarks, and are used only for identification and explanation without intent to infringe. Visit the Taylor & Francis Web site at http://www.taylorandfrancis.com and the CRC Press Web site at http://www.crcpress.com Design by: Pattie Stone Cover by: Saul Roldan The Telecom Handbook by Jane Laino The Telecom Handbook is being used successfully by over 25,000 people who need a quick, basic understanding of the tele- phone systems and services used by today's organizations. The information presented is useful and easy to access. Author Jane Laino's expertise has developed from her early days working at the telephone company to her subsequent creation of DIgby4 Group, Inc., one of New York City's fastest growing telecommunications consulting businesses. Her down-to-earth approach translates con- fusing terms and complex concepts into plain English. This book is an important and unique resource for: Business People who purchase and manage telephone sys- tems and services. Information Technology Professionals who are handed the responsibility for corporate telephone systems. Business Owners who want to understand their company's most critical system. Telecommunications Companies who need to train new staff members. Next Generation Telecom Developers who need to know what people exp

ect from their telephone systems. Students and Educators who will supply the workforce with needed telephony expertise in the 21ST Century. Investors in Telecommunications Companies who want to understand the industry and terminology. Bookstore Owners and Managers who offer rows of com- puter books for sale, but few basic books on telephone systems and services. A quick look through the Table of Contents and Index will preview what's in the book SO you can see if it's right for you. For tips on managing telephone systems, services and expenses visit DIgby 4 Group, Inc.'s web site at www.digby4.com. The Telecom Handbook a iii This book is dedicated to my parents, Fern and Bill Coe. Taylor & Francis Taylor & Francis Group http://taylorandfrancis.com THE TELECOM HANDBOOK Table of Contents PART I Telecommunications Systems Chapter 1 - The Telephone Parts Of The Telephone Telephone Functions Depend Upon the System Older Style Telephones Still in Use Labels Color Trivia Expanding the Number of Buttons Ringing How Does The Telephone Work? Digital VS. Analog Telephones The Continued Importance of the Telephone on Your Desk Chapter 2 - Your Business Telephone System - The PBX What is a PBX? Understanding Your Own System What is the Physical Makeup of the PBX? A Look Inside The PBX Cabinet PBX Shelf PBX Circuit Boards Other Components Inside The PBX Cabinet PBX Sizing and Growth How the PBX Works Earlier PBXs and How they Worked The Telecom Handbook a vii THE TELECOM HANDBOOK Telephone System Design (PBX and Key Systems) PBX Functions (Also Called Features) System Features Accessible To The Desktop Telephone Working With A PBX Expense Control Function of the PBXs Typical Differences Between Key Systems and PBXs Wireless Telephones with a PBX PBX Disaster Recovery Planning Chapter 3 - Purchasing a PBX Identifying Your Organization's Requirements Top 10 (+1) Places To Go Wrong When Planning For And Purchasing A New PBX Identifying the Requirements A PBX Request For Proposal (with sample questions) Chapter 4 - Your Call Cente

r Telephone System - The ACD ACD Hardware ACD System Features Performance Measurement Agent Capabilities Supervisor Capabilities Caller Support Capabilities Network Services (Outside Lines) for ACDs Other Call Center Capabilities Perspective The Call Center Approach to Designing Office Telephone Systems Chapter 5 - Voice Mail and Automated Attendant Definition by How it Sounds to the Caller 18 The Telecom Handbook THE TELECOM HANDBOOK Physical Components of Voice Mail and Automated Attendant Different Ways of Setting it Up Automated Attendant Voice Mail System Components Voice Mail Capabilities for the Caller Voice Mail System Capabilities for the Mailbox Owner Other Voice Mail Features Voice Mail Administration Voice Mail System Implementation and Integration with the PBX Networking Voice Mail Among Multiple Locations Voice Mail Service Bureaus Voice Mail Purchasing Questions Unified Messaging Chapter 6 - Call Accounting and Telemanagement Systems Call Accounting Telemanagement Systems PART II Telecommunications Convergence Chapter 7 - Convergence of Voice and Data Perspective Introduction An Earlier View of Convergence Product Categories Enabling Convergence Engineering-Based Convergence Concepts Putting The Pieces Together The Telecom Handbook THE TELECOM HANDBOOK Where The Network Components Are Located Communications Servers Replacing The "Mainframe" Switch The Concept Of Specialized Networks Applications-Based Convergence Concepts Computer Telephony Applications Development Other Computer Telephony Applications Chapter 8 - Interactive Voice Response Systems How The IVR Provides Information IVR Management Information Available IVR Implementation Chapter 9 - Fax Servers What is a Fax Server? Fax Mail Fax-on-Demand Methods of Document Selection Broadcast Fax Fax Library Management Methods of Creating and Importing Documents Fax-on-Demand and Fax Broadcast Applications Fax-on-Demand Cost Justifications Configuring Fax-on-Demand PART III Telecommunications Transmission and Outside Lines Chapter 10 - Outside Line

s Circuits To Connect Your Telephone System (PBX or Key System) To The Local And Long Distance Companies T-1 Circuit Applications for PBXs = The Telecom Handbook THE TELECOM HANDBOOK Other Types of Telecommunications Circuits (not typically connected to the PBX) Chapter 11 - Transmission Transmission Medium Synchronous and Asynchronous Transmission Modems Multiplexers CSU/DSU Hardware More Transmission Hardware Bandwidth Simplex VS. Duplex Protocols Analog VS. Digital 2-Wire VS. 4-Wire Chapter 12 - Cable Unshielded Twisted Pair Copper Cable The Concept of Speed or Bandwidth UTP Configurations Jacks Power at the Desk Main and Intermediate Distribution Frames Shielded Twisted Pair Screened Twisted Pair Cable Grounding Advantages and Disadvantages of Twisted Pair Copper Cabling Coaxial Cable Fiber Optic Cable Purchasing Cabling and its Installation Building Cabling Systems Cabling Standards The Telecom Handbook xi THE TELECOM HANDBOOK PART IV Telecommunications Industry Chapter 13 - Understanding the Telecommunications Industry Telecommunications Network Services (Outside Lines And Calls) Telecommunications Systems (Equipment) Software And Service Companies Professional Services Outsourcing Resources - Who To Call Chapter 14 - Historical Perspective on The United States Telecommunications Industry Telecommunications Industry History: A Personal Perspective From The Author INDEX xii to The Telecom Handbook Thanks For Your Help Everyone To Harry Newton - founder of Telecom Books and author of Newton's Telecom Dictionary. Harry developed the idea for this book in 1994. He realized the need for a basic book on telecommunications, particularly for people in the computer industries. The book was originally titled "Telephony for Computer Professionals." Harry continues to be an inspira- tion to me and to many others in our industry. To Frank Brogan and Matt Kelsey of CMP for their encourage- ment and patience. To John Jainschigg, editor of Communications Convergence magazine, for sharing his insights on the future for the

chap- ter on Convergence of Voice and Data. To Christine Kern for her support and her cheerful countenance. It's been a pleasure to work with her. To Steve Teta for his patient review of the book from a technical perspective. To Gioia Ambrette and the staff of Newcastle Communications in New York City for their help with the chapters on Voice Mail, Interactive Voice Response, Fax Server and Call Ac- counting. Their company specializes in selling and setting up these applications. To Eric Burger of Snowshore and the International Softswitch Consortium. Eric's help with the chapter on Convergence of Voice and Data was invaluable. To Gordon Fowler and Anthony Abbott for their review and suggestions for the chapter on Convergence of Voice and Data. To Don Stigliano and John Walston of Netversant for their time and help on the PBX Chapter. continued The Telecom Handbook xiii THE TELECOM HANDBOOK To Al Festa and Dan Krych of C&C Sales for their help with the chapter on Cable. To Dave Crozier for his help with the chapter on Cable and his creative suggestions. To Cahal Grennan of Pingtone for his contribution to the chap- ter on Convergence of Voice and Data. To Fran Blackburn for her contribution to the chapter on Auto- matic Call Distributors. Intecom makes ACDs for Call Centers. To Pattie Stone for her meticulous desktop publishing and graphic design services and creative suggestions. Pattie's support has been invaluable in getting this 4th edition ready. To the Staff and Associates of DIgby 4 Group, Inc. who keep our company growing and our clients happy - including Diane Ventimiglia, Jean Fitzpatrick, Laura Taylor, Olga Dawidowicz and Kathy Charlton. To the wonderful clients of DIgby 4 Group, Inc. for their confi- dence in us. To my husband, Rich Laino, for his patience and support. To all of my friends in the telecommunications industry each who has helped me in his own unique way. - Jane Laino, New York City, 2002 xiv The Telecom Handbook THE TELECOM HANDBOOK About the Author Jane Laino is president of DIgby 4 Gr

are similar and the two are "merging," they'll feel right at home. They are wrong. Dead wrong. The phone business is completely different from the computer business. In every possible way. How different they are is reflected in the fact that not one single computer company I can think of has made money in tele- communications. IBM lost over $2 billion. It bought Rolm, the PBX switch maker. It started Satellite Business Systems, the long distance phone company. And, at one stage, IBM even manufac- tured and sold its own PBXs in Europe. All these ventures are gone; closed or sold at a whopping loss. Ditto for Honeywell, which at one stage, owned a collection of interconnect compa- nies - PBX telephone sales, installation and service companies. The telephone industry has fared no better. AT&T lost SO much in its own computer business (it sold its own Unix machines and private-labeled Olivetti MS-DOS PCs) that is was forced to buy NCR to cover its immense computer losses. The local phone companies have fared even worse. When AT&T's Bell system was broken up in 1984 into AT&T and seven "Baby" Bells, the Judge made each of the Baby Bells "holding" companies, called RBOCs (for Regional Bell Operating Compa- nies). This meant presumably, that they were meant to "hold" something. Like AT&T, they thought there was big money in the computer industry - presumably on the philosophy that things unknown are more intriguing that things we know about. Thus, in order to "hold" something, they bought everything in software The Telecom Handbook xvii THE TELECOM HANDBOOK and computer retailing they could get their hands on. Nynex even bought IBM's computer retail stores - the ones IBM couldn't make money on. At one stage, Nynex even tried to compete with IBM's money-losing Prodigy service. Nynex's venture lost oodles, also. Virtually every other RBOC got into software and lost more money than most of us ever dream about. One RBOC bought a software company for $340 million and sold it the following year for around $160 million. Today,

all the RBOCs' computer dalli- ances are gone, at millions of dollars cost to their poor shareholders, who mistakenly thought they bought shares in a "safe utility." To show how different the computing and telecom businesses are, let's look at each management discipline. Let's compare a computer company to a local telephone operating company, Bell or independent. Apologies in advance if this seems trivial. It's not. I don't have the space; but if you want to pursue this fasci- nating subject, e-mail me on [email protected]. Differences between a "computer" company and a local telephone company: Sales. The computer industry is obsessed with selling. Every senior executive in any successful computer company is a great salesman. In contrast, telephone company executives are lousy salesmen. They've never had to be good - all their customers are captive. If you have a business in New York City, who else can you get dial tone from? What choice do you have? The telephone company actually has one "customer." It's called the Public Service Commission, the local state regula- tory agency. That agency determines how much or how little money the phone company makes. The problem is that the local phone company doesn't see the agency as a "customer." It sees the agency as an adversary, an enemy who is always trying to reduce the telephone company's efforts and legiti- mate rewards. So the "sales" approach is always wrong. It's xviii - The Telecom Handbook THE TELECOM HANDBOOK always, "Let me earn more money. Gimme. Gimme. Gimme." It should be, "I'll do this for you and the fine people of this State if you let me earn more money." The nice people who work at the PSC, who earn far less money than the telephone company executives who visit them, naturally resent this high- handed "Gimme. Gimme. Gimme." approach. And they typically do everything within their meager power to mess up the telephone executives' placid and pleasant lives. Innovation. Computer companies only sell stuff if they sell new stuff. To live they must in

novate. Phone companies do not innovate. They have essentially been selling the same service - 3 kilohertz switched phone service - for 120 years. There are a handful of new digital services which businesses, if you're lucky to be located in the right place at the right time, can get T-1, digital Centrex, etc. But the list is miser- ably small. With only a handful of exceptions, the phone industry's new product marketing efforts have failed. Even touch-tone service, introduced into North America in 1963 (over 30 years ago), still has less than 70% penetration. In other words, over 30% of Americans have found touch- tone SO unappealing they don't have it. The irony is that having its customers on touch-tone actually benefits the phone com- panies enormously because it lets them buy cheaper switching equipment and run their equipment fast and more economi- cally. (They should be giving touch-tone away for free). Engineering. There is innovation in the phone industry. It's just that it's internally focused. The phone industry has been quick to buy modern equipment which works better, more reliably, saves labor, etc. Testimony to this is that phone con- versations today sound a lot better than they did ten years ago. And phone systems break a lot less often. As a result, the phone industry (AT&T, the Baby Bells and GTE) have fired over 250,000 people since divestiture, bringing down their costs. You and I, as customers, haven't seen those cost The Telecom Handbook xix THE TELECOM HANDBOOK savings in our bills (with the single exception of long dis- tance phone bills). Think of the cost/speed/performance improvement in your PC over the past ten years; think of the cost/speed/performance in your telephone bills over the same ten years. You should have had a commensurate improve- ment in telephone services. The two technologies are the same. Yet the industries are very different. What happened to all those freed-up monies in the phone industry? Try high sala- ries, waste, large expense accounts and all the millions lost

in failed computer ventures. Executive motivation. If you perform in the computer in- dustry you do well. Your career prospers. Bill Gates says he only wants to hire people who've made serious mistakes. He won't hire anyone from the phone industry. No one in the phone industry makes decisions that fail. They just don't make decisions. The rule in the phone industry is simple: You'll never be penalized for not making a decision. So the ten- dency is never to make a decision. Go to meetings. Commission studies. Go to more meetings. Commission more studies. Don't ever do anything. Here's a true story. New York Telephone employed me as a marketing consultant. I went to the first meeting. I asked, "Who's your largest prospect?" It was a customer who could give New York Telephone (now called Nynex) about $115 million a year in revenues and about $15 million to $20 million in profits a year. I asked, "Who's the salesman on the account?" Turns out that New York Telephone didn't have a sales- man dedicated full-time to the account, and worse, the customer hadn't been visited in over four months. I suggested that they appoint someone. This recommendation took rocket science intellect on my part. Everyone on the third level management The Telecom Handbook THE TELECOM HANDBOOK agreed. The vice president (fifth level) agreed this was a good idea. But the assistant vice president (fourth level) said that he wanted "to think about it" and have a meeting or two. I gave him till 5 PM the following day. At 5:05 PM, I walked into his office and asked what his decision was? He said he needed more time to think. I said there was no more time. I went upstairs to the vice president, who had already warned me that his $140,000 a year AVP was "use- less." I told the VP that his AVP was being stupid and I recommended that he fire him on the spot. The VP answered, "You're 100% right. The man is stu- pid. He should be fired. But we can't do that around here." I immediately handed in my resignation. A couple of years later, I met the AVP. H

e had been given a promotion, a higher salary and moved to Nynex! I have no idea if they ever sold the account. Customer relations. Computer companies want to please their customers. Telephone companies want to keep their cus- tomers from complaining. The BIG thing that gets a telephone executive's attention is a complaint letter to the local PSC, or a complaint letter to the president of the telephone com- pany. Computer companies want the excitement of new sales. Telephone companies want the peace of non-complaining cus- tomers who unquestioningly pay their monthly phone bills. Education. Go to any bookstore. You'll find acres of books on computers. Try to find the books on telephones. This is not accidental. The telephone industry figured long ago that if it could keep its customers in the dark with a "Trust me, Trust me," philosophy, they could sell them and charge whatever they wanted. You don't believe me? Find your company's last month's phone bill. Ask yourself what all the line items mean? Ask yourself, "Are you really using what you're pay- ing for?" Now, call your local phone company's business office and ask them to explain what's on the bill. Good luck. The Telecom Handbook xxi THE TELECOM HANDBOOK It's not because telephone services are complex. Computers are much more complex. It's because the telephone industry deliberately chooses to obfuscate how it bills for its products and services. Common Mistakes That's enough of the differences. Let's list a few of the more common mistakes computer companies make when dealing with phone companies: Motivation. "If I do this," the computer company says, "your phone company will get $X thousand more per month. So let's do this joint deal together." Says the phone company, "Seems like a good idea to me. Let me study it." Translation: "When we've studied it to death in our various million com- mittees, we might do a field trial. But the trial will be set up in such a way that it will fail. And then I won't ever have to make a decision to go ahead or not go ahea

d." You, as an outsider, cannot assume that phone compa- nies are motivated to increase their sales and their earnings. Remember, their earnings are limited by the local PSC. Whatever you do for them and I stress whatever you do for them - you can never do what the local PSC can do much less painlessly and with much greater effect; i.e., get them money. Moreover, no phone company executive has any significant number of shares in his own company. Even at the highest level. Virtually anyone that has ever relied on the phone com- pany to do anything in a speedy, intelligent manner has gone broke waiting. I can present you with lists of companies. The acute lack of motivation translates into deliberate glacial speed, which will kill any outsider's motivation. Speed. The phone company works at its pace, not yours. You may build yourself a palatial $100 million office complex. xxii % The Telecom Handbook THE TELECOM HANDBOOK You want to be in on January 1. All your contractors may be on some form of motivation, bound by a written contract. Except one. The phone company. Your "written contract" with the phone company is the tariff which the phone company has filed at the PSC. That tariff typically states that if they're late installing their lines, tough. You wait. You can scream. And screaming often works. But it's very exhausting. In fact, dealing with the phone industry is always exhausting. In short, don't believe any promises they make about delivery. Ever. Homegrown. The phone industry never hires from outside its own industry. That's not 100% true. They have been hir- ing some low level, not-too-bright executives. But you won't find any senior executives. Even IBM went outside for its new boss. You won't find that happening in the phone indus- try. The executives are very protective of their own secure, overpaid positions after all, you, the customer, can still make a phone call, etc. So why should you complain? You some- times sit in meetings with these people, as I have done, and wonder which planet they just s

tepped off. I think it's getting worse. To "fire" those 250,000 people, they offered many of them retirement and departure finan- cial incentives that you'd have to be just plain stupid not to accept. You could argue, as a result, that the average IQ of the country's telephone company executives has dropped. You wouldn't be wrong. It's sad. Is Any of This Going to Change? The good news is that it will. It won't change because com- panies like Nynex change. They won't. They'll still be glacial, visionless, unmotivated and difficult to deal with. But they'll get competition. Technology is the great change merchant. It always has been in telecommunications. And it always will be. Technol- ogy brought MCI, Sprint and hundreds of others into long distance. That industry improved. Ditto for telephone equipment The Telecom Handbook xxiii THE TELECOM HANDBOOK you put in your office. Ditto for fax machines, etc. Technology will bring competition to the local business. You'll buy local ser- vice from MCI, and dozens of others. They'll want your business and they'll do reasonable and wonderful things to get it. They'll cooperate with you in your computer telephony projects. They'll set up intelligent developer programs. They'll let you experiment. They'll let you put your equipment in their offices. They'll even take care of your equipment. Some of this might rub off onto some of the nation's phone companies. Bell Atlantic and BellSouth are acting more progressive. There is hope, yet. Just don't pin your business plan on it. Harry Newton New York City, June, 1994 xxiv of The Telecom Handbook PART I Telecommunications Systems The Telecom Handbook - 1 Taylor & Francis Taylor & Francis Group http://taylorandfrancis.com CHAPTER 1. The Telephone Newton's Telecom Dictionary defines the telephone as a truly remarkable invention that does the following things: When you lift the receiver, it signals the local system that you wish to use the worldwide phone system. It indicates that the phone system is ready for you to dial by giving

you a dial tone. It sends the number of the telephone to be called. It indicates the progress of your call through tones: ringing, busy, etc. It rings to alert you to an incoming call. It transforms your speech into electrical signals for transmis- sion to a distant point and translates the electrical signals it receives back into the human voice for you to hear. It automatically adjusts for changes in the power supplied to it. When you hang up, it signals the telephone system that you are finished. The telephone is also referred to as a telephone instrument, station or set. There are single-line telephones and multi-line tele- phones (also called multi-button telephones). These telephones can be analog or digital and you cannot always tell which is which by appearance. Telephones work with outside telephone lines from the local telephone company or as extensions from a business telephone system (PBX or Key System). The telephone is designed to operate under a wide range of electrical, mechanical and acoustical conditions. Some of the de- sign parameters are dictated by human factors such as sound levels of the human voice and handset dimensions (the handset is also The Telecom Handbook * 3 THE TELEPHONE called the telephone receiver). Some parameters are historical carryovers such as ringing voltage and frequency. Others, such as the minimum line current for satisfactory carbon transmitter and relay operation, are dictated by the physical properties of the materials used in the telephone. Telephones in use today are of different vintages. The more recently manufactured telephones substitute microphones for some of the materials such as carbon transmitters still found in many older telephones in use. The following pictures show a single-line telephone (Figure 1.1) and a multi-line telephone (Figure 1.2). As you can see, they vary somewhat in appearance, but have some things in common. Figure 1.1 - Traditional Single Line Telephone (Also called 2500 Set) You speak into the Transmitter You listen through the Recei

ver Figure 1.2 - Multi Line Telephone The Telecom Handbook CHAPTER 1 Parts Of The Telephone First, we will point out the things you can see, and next we will get to what is inside. Here is a diagram of a typical tele- phone with its external parts labeled. Figure 1.3 Parts of the Telephone MOUNTING SWITCH HOOK (Connects (Under the Handset) to Wall) DISPLAY 12:42 MESSAGE WAITING EXT 1236 HANDSET EXT 1235 EXT 1234 SPEAKER EXT 1233 SPEED TRANS FEATURE BUTTONS DIAL PAD HANDSET CORD The telephone handset, also called the receiver. In fact, it includes both the receiver enabling you to hear and the trans- mitter through which you speak. It may also have a volume control or a bar that you can depress to mute either the re- ceiving or transmitting capability. (Buttons on the telephone may also control these functions.) Handsets come in different shapes and sizes and are usually made to work with a telephone from a specific manufacturer. The Telecom Handbook * 5 THE TELEPHONE The handset may be directly wired (also called hardwired) to the telephone cord, which in turn is directly wired into the telephone instrument, or there may be a plastic modular con- nector at one or both ends of the cord. People who spend the entire day on the telephone such as customer service representatives, stock brokerage trad- ers and switchboard attendants often use a headset instead of a handset. On many telephones, you must leave the hand- set attached and "off the hook" while using a headset, which is cumbersome. b. The handset cord. Also known as the curly cord. This often gets very twisted which can break or damage the wires inside causing interference (static or "noise" on the line). Holding it up and letting the handset dangle at the end, enabling the cord to unwind, can straighten it out. As mentioned above, most handsets are connected to the telephone with a small plastic modular connector that plugs into a jack opening on the telephone. Some handsets are hardwired into the telephone and cannot be unplugged. C. The mounting cord. A s

traight cord (cable), usually gray or a translucent gray called silver satin. Typical lengths are 6 feet, 9 feet, 13 feet and 25 feet. This cord sometimes has a modular connector at each end, one plugging into a jack opening on the telephone and the other plugging into a jack opening in the wall. In some cases the mounting cord is wired directly to the telephone or the wall or to both and cannot be unplugged. The dial pad. Also called the keypad, touch-tone pad, touch- tone buttons or DTMF pad ("DTMF" stands for dual tone multi-frequency, referring to the touch-tone signals). Most telephones use the DTMF method for sending a telephone number to the telecommunications service provider. The lo- cal telephone company central office and the business telephone system (PBX) must have the capability to process 6 52 The Telecom Handbook CHAPTER 1 these tones. The telephone is equipped with the dial pad having 12 buttons that represent the numbers 0 through 9 and the symbols * and #. Pressing one of the buttons causes an electronic circuit to generate two tones. There is a low-fre- quency tone for each row and a high-frequency tone for each column. Pressing button number 5, for example, generates a 770-Hz tone and a 1,336-Hz tone. By using this dual tone method, only seven tones produce 12 unique combinations. The frequencies and the dial pad layout have been interna- tionally standardized, but the tolerances for variations in frequencies may vary in different countries. The touchtone signals are used not only to dial telephone numbers, but also to interact with Voice Processing systems such as Voice Mail, Automated Attendant. (for Sales press 1, for Service press 2, etc.) and Interactive Voice Response. Some telephones may have a round rotary dial, but this is becoming less common. The signals sent out by a rotary dial telephone are called dial pulse. Rotary dial telephones are still in use. In general, their dial pulses are not recognized by voice processing systems. Touchtones on A Rotary Outside Line Some telephones h

ave a little switch on the side, which can be set to dial pulse or DTMF. If the outside line is rotary but you want to use the touchtone buttons, it con- verts the signals being emitted by the telephone from DTMF to dial pulse. This is necessary if the local telephone com- pany central office cannot accept DTMF signals, which is increasingly rare in the United States. The dial pad is still touch-tone in appearance, not rotary. When you dial the called telephone number on the touch-tone pad, it will take longer for the telephone to send out the dial pulses (about as long as it would take if you were actually using a rotary telephone). You can usually hear the sounds of the tele- phone "pulsing out" while you are waiting. The Telecom Handbook 4 7 THE TELEPHONE Some of the newer voice processing systems use voice rec- ognition (Say "Yes" for the Sales Department.) e. The feature buttons, also known as feature keys or function keys. These can serve a variety of functions. They enable different outside lines and extensions to be answered. They may activate telephone system functions such as call trans- fer, call conferencing, call forwarding, etc. They can also be used to speed dial frequently called numbers. Every telephone system manufacturer treats these feature buttons differently, SO what you learn about one system may not apply to an- other. Some feature buttons are flexible, meaning that they can be programmed for a variety of functions. Some are fixed, meaning they can provide only a specific function. Some systems have soft keys meaning that the same button per- forms different functions at different times. f. The display, also known as the LCD (liquid crystal dis- play). Not all telephones have displays, although most newer ones do. All business telephone system manufac- turers provide them, but the display telephones may cost more. In most cases they are worth the investment since operating the telephone on a business telephone system without the benefit of the information provided in the dis- play can be c

umbersome. Different systems provide different information in the display. Some show the date and time when the telephone is not in use. Some provide instruction prompts to the person attempting to use sys- tem functions. Most show the name or extension number of the person calling you, if the call is coming from some- one else within your office. Some show the name or telephone number of the person calling you from another location (known as Caller ID or ANI - automatic number identification - if this information is being delivered to your PBX over your outside lines.). A few systems enable you to leave a pre-selected message SO that when some- one calls your telephone from within your office, his 8 $ The Telecom Handbook CHAPTER 1 display will read that you are "out to lunch" or "in a meet- ing." Other systems enable a secretary to send a silent message to the boss while the boss is on another call, al- though this is not common. As with the feature buttons, the important thing to remember is that telephones and telephone systems from different manufacturers use the display differently. No two are exactly the same. g. Lights (also called lamps or LEDs - light emitting diodes) On some systems there may not be a light, but an LCD (liq- uid crystal display) indicator instead. Most people find the lights easier to see than the LCD. The purpose of the light or LCD is to indicate the status of a call in progress on one of the outside lines or extensions. The light may be red, green, white or amber and more than one color may be lit at the same time. This differs considerably depending upon the manufacturer and model of the system. A light flashing on and off slowly may indicate a new incoming call and is some- times accompanied by an audible ring. If the same extension appears on more than one telephone it may simply flash at some telephones and audibly ring on others. A steady light usually indicates that the line is in use on either your tele- phone or another telephone that picks up the same line. A rhythmically f

lickering light may indicate that a call is on hold. Some telephones have a light next to the button of the extension number that remains lit even when the telephone is not in use. h. The switchhook. This refers to those two little plastic but- tons that press down on a conventional telephone when you hang up the receiver. When you hang up you are actually breaking an electrical circuit that connected you to the per- son at the other end while you were talking. On some telephones, the switchhook may be a single bar that depresses when you hang up. Other telephones have a magnetic switchhook inside the telephone, directly under the receiver when it is hung up, that cannot be seen from the outside. In The Telecom Handbook 30 9 THE TELEPHONE very old movies, we often see someone frantically tapping the switchhook trying to get help as the intruder is banging on the front door. This method was once used to reach an "operator" or switchboard attendant. Instead you would now dial 0. In telephone systems introduced in the 1960's and 1970's, the switchhook was used as a means of activating the system functions such as call transfer. If you held the switchhook down for a second too long, you'd disconnect the call! These functions are now accomplished more easily with feature buttons. Speaker. Most multi-line and a few single-line telephones are equipped with some type of speaker. A speakerphone enables the person using the telephone to have hands-free conversation with another person at a distant location with- out lifting the handset. Some speakers are one way only. This may be called a monitor rather than a speakerphone, which is two-way. The monitor enables the person using the tele- phone to dial out or wait on hold without lifting the handset. They can hear what is on the open line, but cannot speak back to the caller without picking up the handset. Another capability, also called monitoring, enables others in the room to hear both sides of a telephone call in progress, while the person in the room who is speaking us

es the handset and the caller at the other end does not sense that he is on a speaker. This is sometimes used for training staff members on how to handle particular types of calls. Speakers may also be used for internal intercom communication only, where someone in on the same premises can call you and his voice will be projected over the speaker. Some systems will allow you to answer back hands-free while others will not. Not surpris- ingly, this feature is known as hands free answer back! j. Message waiting indicator. If the system is working with a Voice Mail system, this lamp or LCD indicator lets you know that you have a message waiting in your Voice Mailbox. There 10 The Telecom Handbook CHAPTER 1 may also be a message on the display of the telephone such as MW for "message waiting." Any of these may also indicate a message waiting at the reception desk or message desk if there is no Voice Mail. Although this use is less common most tele- phone systems enable a receptionist to manually activate a message-waiting indicator on any telephone in the system. In some systems, the message waiting indicator is a button that, when pressed, will automatically connect you to the Voice Mail system or receptionist to retrieve your messages. k. Base of the telephone; telephone housing. This is gener- ally a molded plastic casing designed to house a specific type of telephone. Faceplate or Face Layout. Most telephones that work with business telephone systems enable you to print a layout of the front (face) of the telephone including the extension num- bers and system features that correspond to each button. This printed layout may slip into place over the buttons and under a clear plastic cover that is often called the faceplate. Telephone Functions Depend Upon the System Another way to define the telephone is to describe its func- tions. Remember that what a telephone is able to do depends in a large part on the system to which it is connected. Some telephones are connected via cable in the walls to a business telephone

system (either a key system or a PBX whose control cabinet is located on the business' premises). Some tele- phones in businesses or residences are connected via cable in the walls to cable in the street and back to the local telephone com- pany central office where central office-based switching equipment is located. Some common functions that many telephones can perform are found in the chapter on PBX. The Telecom Handbook * 11 THE TELEPHONE Older Style Telephones Still in Use You may hear some of the following terminology referring to the telephone that originated within the Bell System and is still in use today: A single-line telephone such as one you may have in your home is sometimes called a CV or a 500 set (rotary), or a 2500 set (touch-tone). It can be a desk or a wall-mounted model. The older electromechanical multi-line telephones, which are becoming scarce, were called K sets or key sets, referring to the keys or buttons. Each has a red hold button. The KV has six buttons. Then there is a K-10, a K-20 and a K-30, each with that number of buttons. The term call director is also used to refer to a large multi-line telephone. Different geographic areas of the Bell System sometimes used slightly different terms for the same telephone, such as KK6, which was Southwestern Bell's term for New York Telephone's KV. (Note: Southwestern Bell now part of SBC and New York Telephone part of Verizon.) Collectively, this type of electromechanical key equipment was known as 1A2 equipment. The hold button and lights on the phone were controlled by circuit boards in the telephone equip- ment room. Naming of telephones today is even less standard than in the past. Each manufacturer makes up names for its own telephone instruments. Sometimes the names mean something, such as a model number referring to the number of buttons on the telephone. Labels An important aspect of the telephone is how it is labeled. Some manufacturers provide printed labels to indicate the ex- tension number or feature of each button on the teleph

one. 12 The Telecom Handbook CHAPTER 1 Other manufacturers do not and the numbers and features are often written in pencil which looks very unprofessional, both for the installation company and the organization using the system. Telephones often start out neatly labeled, but get messy as changes are made to the features or extensions. Many busi- ness telephone systems are incorrectly labeled which makes them harder to use. Some telephones enable you to replace all button labels with a single sheet, which slips under the clear faceplate on the tele- phone. Others require that you create a single tiny little label and take off each individual button to replace the label. This can be time consuming when making many changes to a group of tele- phones. Others separate the labels into strips, with one paper strip per row of buttons. Color Trivia The single-line telephones that used to be supplied by the local Bell System company pre-1970 came in a variety of colors: white, black, red, ivory, pink, beige, blue, aqua, green and yel- low. In the 1980's the color choices for business and residence telephones were typically beige or ash, sometimes gray. Now black or charcoal is back as the new color of choice as organiza- tions grew tired of having the telephones always look like they needed a good cleaning. (Note that the desktop computer is slowly following suit with beige giving way to charcoal gray.) Expanding the Number of Buttons Some multi-line business telephones can change from ten to twenty buttons by "popping out" the button strips (called key strips) and inserting a panel with more buttons. Other business telephones can add one or more modules to add more buttons. On other systems the only way to get more buttons on the tele- phone is to purchase a new telephone. The Telecom Handbook 13 THE TELEPHONE Ringing One thing you can't tell by looking at a telephone is how the ring is going to sound. Yet this is a sound you are going to be listening to many times a day for many years. Telephone system manufacturers diff

erentiate ringing sounds in different ways. One is the "cadence". For example, a call coming in from outside may be "riiiiing - riiiiing" while an internal call may be "ring ring - ring ring" (short little bursts of ringing in the same time interval that an outside call takes to ring two long rings). Another differentiator is pitch. Some rings have a high pitch changing to a low and others start with a low and change to a high. Some actually have different sounds. Different ringing for internal and outside calls is becom- ing less important as information on the display lets you know whether the caller is internal or from the outside world. Differentiated ringing among a group of telephones all in the same area is often useful. That way if you are not sitting right at your desk, it is still possible to know that it is your telephone that is ringing. Most telephones do not enable you to have a different ringing sound for each line or extension appearing on a multi- line telephone. More detail on the functions of the telephone and more functions of business telephone systems are described in the chapter on the PBX. How Does The Telephone Work? Now, let's get to what is inside the telephone. Remember that these components described are commonly found in the older traditional telephones. We are providing this information to lend an historical perspective. Most of today's telephone systems sub- stitute electronic components to emulate these functions. 14 & The Telecom Handbook CHAPTER 1 Figure 1.4 The Transmitter DIAPHRAGM CONNECTION TO FRONT AND BACK OF CAPSULE CARBON SPEECH GRANULES PRESSURE HANDSET VARIATIONS HOUSING TRANSMITTER FLEXIBLE SUPPORT COUPLING a. The transmitter. (Figure 1.4) The transmitter is the ear of the telephone in that it "hears" the voice of the person speaking into it. The transmitter is a miniature carbon pile rheostat. A rheostat is a device that controls an electric current by vary- ing the resistance in the circuit, similar to the action of a dim- mer switch control. The variations in sound

pressure from the voice vibrating against the diaphragm change the com- pression of the carbon granules. This varies the resistance of the transmitter. The transmitter has two contacts that are in- sulated from each other. Current can only flow through the carbon granules. As sound pressure from the voice presses against the diaphragm, the carbon is more closely compressed within the chamber. Compressing the carbon granules low- ers the resistance of the transmitter resulting in more current flow through the transmitter circuit. When the pressure on the diaphragm is released, it momentarily snaps out farther than its original position. The carbon is under less pressure than normal and the resistance of the transmitter is momen- tarily greater. The current flow decreases. The Telecom Handbook 35 15 THE TELEPHONE The diaphragm of a transmitter is made of lightweight phosphor bronze, duraluminum or a similar material. Either an extra inner cone of the same material strengthens the cen- ter or it is corrugated to act as a stabilizer. The flexible outer edge is securely clamped in the transmitter housing. This de- sign enables the diaphragm to move in and out at the center like a piston. Since the diaphragm is sensitive to sound waves, the carbon granules are compressed and released as the cor- responding pressure from the sound wave's changes. The telephone transmitters in use today are, in principle, like the ones invented more than 100 years ago by Thomas Edison. Many modern electronic telephones use real micro- phones connected to related speech processing equipment to vary the line current. Small microchips allow economy and space saving, enabling inexpensive, high quality "throwaway" telephones. The output now generated by microchip-based telephones must emulate the same variations created by the carbon granule type of transmitter. What is known as the basic 500 set, a single-line tele- phone like the one that was in use in most homes, has dictated the industry's electrical standard for the telephone instrument

and all related signal processing equipment. All types of - and 4-wire circuits are still designed around that 500 set. b. The receiver (Figure 1.5). The receiver is the "mouth" of the telephone in that it speaks into the ear of the person using the telephone. It also contains a diaphragm whose movement is caused by the strengthening and weakening of the field cre- ated by the magnet within the receiver. The receiver converts the varying electrical current representing the transmitted speech signal to variations in air pressure perceived as sound by the human ear. An electromagnetic receiver consists of coils of many turns of fine wire wound on permanently mag- netized soft iron cores that drive an armature. The armature is a diaphragm made of a soft iron material. 16 The Telecom Handbook CHAPTER 1 Figure 1.5 The Receiver ELECTROMAGNETIC HORSESHOE PLASTIC CAP PERMANENT MAGNET THIN IRON DIAPHRAGM When someone speaks a word into a transmitter, the cur- rent flow in the circuit is alternately increased and decreased as the moving electrode moves in and out of the carbon cham- ber. A requirement for an electromagnetic receiver is a permanent magnet to provide a constant bias field for the varying electromagnetic field to work against. Otherwise, both positive and negative currents would push the armature in the same direction. The varying electrical current repre- senting speech flows through coils and produces a varying electromagnetic field. It alternately aids and opposes the per- manent magnetic field; thus, it alternately increases and decreases the total magnetic field acting on the diaphragm. This causes the diaphragm to vibrate in step with the varying current and moves the air to reproduce the original speech that caused the current changes. Other types of receivers op- erate similarly, except that the armature is a separate part and The Telecom Handbook @ 17 THE TELEPHONE is connected to a conical non-magnetic diaphragm. The rock- ing action of the armature causes the aluminum diaphragm to vibrate to repro

duce the original speech. In some telephones this receiver is created with the use of microprocessors. The electromagnetic receiver was a central element of Alexander Graham Bell's original telephone patent. Part of the design of the telephone handset that enables you to hear your own voice while talking is called side tone or side noise. The reason for this is to give you some feed- back that the telephone is working. Too much side tone causes an echo. C. The ringer. There is a wide variety in types of ringers. Tele- phones run on DC (direct current) where electrons flow in one direction. The bell or ringer operates on AC (alternating current), which means that electrons are moving in two dif- ferent directions to activate the bell. This AC sent on the local loop (telephone line) is called ring generator (90 to 105 volts AC at 20-Hz). Minus 48 volts DC is always on the line, which is used to operate the telephone after is answered. There is a good analogy for understanding these electri- cal signals. Envision a garden hose. The hose represents the wire. The water is the current. The water pressure is the volt- age (electrical pressure). Stepping on the hose with your foot is equivalent to resistance on an electrical circuit. d. Microprocessors. The microprocessors in electronic tele- phones may replace any of the above internal components and may also add additional capabilities and functions to the telephone, such as speed dialing, etc. Many telephones look the same, but there is wide variation in the capabilities and prices. You can buy a throwaway single- line telephone for less than ten dollars or a multi-line multi-featured telephone to work with a business telephone sys- tem for six hundred dollars. As with many manufactured items, there is variation in the quality of the components that is reflected in the price. The price also tends to be higher on the proprietary 18 is The Telecom Handbook CHAPTER 1 telephones, which work with a specific manufacturer's system, even though they may look the same as those

you, buy in your neighborhood telephone store. Digital vs. Analog Telephones Some telephones are digital and others are analog. The dis- tinction has to do with how the speech is processed in the telephone before it is sent over the line back to the business tele- phone system or the local telephone company central office. Voice starts as analog, represented by a sine wave (Figure 1.6). In many systems, the voice is transmitted in the analog form. In systems that convert the voice to a digital signal, the voice signal is sampled 8,000 times per second. Each sample is assigned a numerical equivalent, some combination of zeroes and ones. The binary numbering system uses only zeroes and ones to rep- resent all numbers. Each sample is a voltage reading, which is given a numeric value and changed into binary form Figure 1.7). When the signal reaches its destination, it is converted back to analog SO that the human ear can hear it. Figure 1.6 - Compliments of Siemens Digital Telphony provide by Clem Napolitano The Telecom Handbook $8 19 THE TELEPHONE Figure 1.7 SAMPLINGS CONVERTED TO BINARY NUMBERS REPRESENTING THE AMPLITUDE AT EACH SAMPLING POINT - Compliments of Siemens Digital Telphony provide by Clem Napolitano The telephone systems themselves are also either analog or digital, but this has to do with how the signals are moved around within the system control cabinet. The systems manufactured in recent years are digital although some analog systems remain in operation. It is possible for a digital telephone system to have analog telephones. Analog telephones may be similar in func- tion and appearance to the digital telephones. The Continued Importance of the Telephone on Your Desk Despite the increasing ubiquity of desktop computers and e-mail, it can be argued that the telephone is still the most important communications device. It is telling that the movers and shakers of industry often relegate computer functions to their assistants, and do business solely with the telephone. Also, the preference of one teleph

one over another is most often the decid- ing factor in a new telephone system purchase decision. 20 The Telecom Handbook CHAPTER 2 Your Business Telephone System - The PBX What is a PBX? PBX is the term used for most business telephone systems. The letters stand for Private Branch Exchange. Private means that the system is on your premises as opposed to public mean- ing a similar system used by a telephone company. Branch refers to the fact that the cables connected to the PBX branch out to each office desktop, connecting the telephones to the PBX. Ex- change refers to the activity going on within the PBX known as switching (or exchanging) connections between telephones and outside lines that connect your PBX to the outside world and your calls to telephones at the other end of the call. The PBX is also called a switch which is short for switching system. When a call comes in for you, it may arrive on one of many outside lines connected to your organization's PBX. The switch- ing function in the PBX is what enables any of these outside lines to be connected to your particular telephone. Conversely, when you dial "9" to place an outgoing call, your telephone can be connected to any one of many outside lines, also through switching. If it were not for switching, every single telephone would have to have its own separate outside line which would be costly and inefficient. Switching enables a greater number of tele- phones to share a smaller number of outside lines since not everyone will be using those lines at the same time. Switching is also used by the telephone companies who do not expect every single one of their subscribers to use the tele- phone at the same time. The Telecom Handbook 85 21 THE PBX Understanding Your Own System In terms of thinking about what a PBX can do, it is important to remember that each manufacturer's PBX is different and has its strengths and weaknesses. One PBX may be outstanding in some areas but not in others. When working with a particular PBX, the more you understand it, the bett

er you will be able to make it work to complement your operations. Each telephone system installation company has people on staff who understand the PBX their company sells. If a company sells or supports too many different PBXs, the likelihood of staff knowing any one of them well diminishes. Most telephone installation companies' knowledge is based upon the collective experience of their staff. No one person knows everything there is to know about a particular PBX. There is just too much to know and it changes with different software re- leases and system configurations. What the telephone installa- tion company does not know, you may be able to find out from the PBX manufacturer. If you are responsible for managing a telephone system, you may wish to join a user group. These groups exist for all of the major PBXs. People using systems in real world environments are often the best source of information on a particular system. What is the Physical Makeup of the PBX? The PBX is made up of hardware and software components that serve the purpose of connecting the telephones to outside lines enabling the completion of incoming and outgoing calls. The PBX also connects internal calls from one telephone in the office to another. The PBX is typically housed in the telecommunications equip- ment room or closet on the premises of an organization. It is comprised of one or more metal cabinets housing the electronic components. PBXs from different manufacturers may look dif- ferent. Some cabinets are the size and shape of a refrigerator and 22 is The Telecom Handbook CHAPTER 2 may line up side-by-side in the larger systems. Some are modu- lar, with each module stacking on top of another, three or four high. A smaller PBX cabinet may mount on the wall. Some cabi- nets have metal doors SO you cannot see inside and others have black plexiglass doors showing off the blinking colored lights and complex looking circuit boards inside. Here is an example of what a PBX may look like: Figure 2.1 Appearance of Typical PBX Cabinet 4 S

helves With Circuit Boards Inside the PBX are shelves with slots into which circuit boards are placed. These circuit boards have different functions. Some control the telephones, some control the outside lines, but all work together to carry out the functions of the PBX. The Telecom Handbook 23 THE PBX A Look Inside The PBX Cabinet When referring to the telephone system, we include the tele- phones, the cable and the PBX control cabinet, but here the focus is on the cabinet and its contents. The equipment housed in this cabinet connects the telephones within the office to the telephone lines and the world outside the office. PBX Shelf Each cabinet or cabinet module contains one or more shelves. Avaya (formerly Lucent Technologies) sometimes calls the shelf a carrier, but most other companies call it a shelf. The shelf is made up of a group of slots into which the circuit boards fit. Some systems have different slots for different types of circuit boards fit. Other systems may have universal slots that can accept more than one type of circuit board. Each PBX has a numbering scheme SO that the location of each shelf and slot (and cabinet, if more than one) can be identi- fied. The numbering scheme also includes the actual ports on each circuit board. Note: These numbers are typically labeled on each cable connecting the PBX to the telephones (in the tele- phone equipment room). For example 01-04-08 may represent the 8th port on the 4th circuit board on the first shelf. Some sys- tem cabinets come equipped with all of the shelves and others do not, requiring future purchase of additional shelves as needed. A shelf can cost several thousand dollars or more, SO it is important to understand how each PBX is put together when it is installed to avoid surprises when its time to expand or make changes. Many PBX manufacturers build their system in stackable mod- ules. A module combines the exterior cabinetry with the shelfinside. This is becoming more common with newer systems than the older "refrigerator size" cabinet, al

trunks and DID trunks on the same board. This creates efficien- cies in the use of the ports and therefore can lower the cost in terms of the total number of circuit boards to be purchased. It can also save space (sometimes called real estate) within the PBX cabinet. Note: The trunks that use the above types of circuit boards are sometimes collectively referred to as copper trunks or ana- log trunks to distinguish them from the outside lines that are delivered on the T-1s, which is common in PBXs today. Copper trunks are still used for back up. The cost of T-1s has dropped dramatically in recent years, SO T-1 has become the more preva- lent method of delivering the outside lines to the PBX. T-1 Circuit Boards A T-1 is a high-capacity circuit using two pairs of wires, en- abling the transmission of up to 24 voice conversations at one time. In order for it to do this, a piece of hardware called a mul- tiplexer is required at each end. The T-1 circuit board is a multiplexer that fits right into the PBX shelf. In some older PBXs the T-1 circuit card must be placed on a shelf specifically designed to handle it. If you are going to use a T-1, you may need to buy a separate shelf for it. Each PBX has limits, SO find out how many separate T-1s your PBX can hold. You may hear the term channel bank which is a multiplexer external to the PBX. The channel bank can be used if your PBX does not have T-1 circuit board capability. PRI/ISDN Circuit Boards Most PBXs can accept ISDN (Integrated Services Digital Net- work) lines. The circuit board may be for a PRI (Primary Rate 26 di The Telecom Handbook CHAPTER 2 Interface) ISDN line which has 23 B channels plus one D chan- nel. A few PBXs can also accept BRI (Basic Rate Interface) ISDN lines with 2 B channels plus one D channel although the BRI lines are seldom found in a PBX. The ISDN lines can be used for voice conversations and data transmissions. T-1/PRI Circuit Boards On newer PBXs, the same circuit board is used for both T-1 and PRI. Tie-Line Circuit Boards Tie-lines are poi

nt-to-point lines connecting two PBXs SO that the users of both systems may communicate without dialing an outside call. Some systems have separate circuit boards for these tie-lines. Most systems use a circuit board which handles two, four or eight tie-lines. Digital Telephone Circuit Boards Most telephone systems now use digital telephones. This means that the analog voice signal converts to a digital form right in the telephone and travels back to the PBX cabinet in a digital form (combinations of ones and zeroes). For every 8, 16 or 32 of these telephones in the system it is necessary to have a digital telephone circuit board. This may also be called a digital station board. Each port on the board corresponds to a specific digital desktop telephone in the system. Every telephone has an associ- ated numeric location in the PBX cabinet indicating the port, the circuit card and the shelf. Analog Telephone Circuit Boards Most telephone systems are installed with at least one analog circuit board with ports for either 8 or 16 analog telephones. Many single-line telephones are analog. The voice signal is sent from the telephone to the PBX circuit board in an analog form. The Telecom Handbook 12 27 THE PBX The analog ports provide analog extensions required for us- ing fax machines and computer modems through the PBX. There are differences of opinion as to whether or not faxes and modems are best run through the PBX or through separate outside lines. It is believed that some PBXs may slow down the data transmissions. Most PBX manufacturers will not guarantee throughput of data beyond a certain speed. If you expect to have computers and fax machines go through the PBX, it is important to find out what speeds can be expected. You may decide to bypass the PBX. Some systems also use analog ports for interfacing with a Voice Mail or Automated Attendant system although smoother integration is accomplished with a digital interface. DTMF Circuit Boards DTMF (standing for Dual-Tone Multi-Frequency, also known as Touch-tone)

signaling requires a separate circuit board within the PBX with DTMF receivers. If you have to wait too long for PBX dial tone after you lift your telephone handset, you may need more DTMF receivers. The receiver is engaged when some- one within the system is dialing a telephone number and is freed up after the dialing is completed. Common Control Circuit Boards These circuit boards house the central processing capability of the PBX. Most PBXs now have common control circuit boards on every shelf, which is a distributed type of processing. Many of the pre-1980's PBXs had the common control on a single shelf only. If it failed, the entire system failed. Other Components Inside The PBX Cabinet You may see a power supply, a fan and a variety of other electronic components within the PBX cabinet. The Voice Mail electronics may also reside within the cabinet. 28 20 The Telecom Handbook CHAPTER 2 It is important to remember that the circuit boards, like the telephones, are specific to a particular manufacturer's PBX. They are not interchangeable with other PBX's boards. They may not even be interchangeable with circuit boards of other PBX mod- els in the same manufacturer's product line. The PBX also incorporates a CPU (Central Processing Unit), the "brains" of the PBX and a power supply. PBX Sizing and Growth When planning the purchase of a PBX, growth capability is a major consideration. Although they may be modular in design, in terms of telephones and outside lines that can be connected to the system, PBXs have a maximum capacity. In most systems, one port represents the ability to connect one telephone or one outside line. A 400 port system can accommodate a total combi- nation of 400 outside lines and telephones. There are no precise ratios in terms of how many outside lines are required for the number of telephones. A conservative ratio would be 25 outside lines (for incoming and outgoing calls) for every 100 telephones. If there are not a lot of calls, 10 lines may be sufficient. If it's very busy, more than 25

may be needed. There are statistical tables and software programs available to enable you to judge the total number of outside lines needed. Using these statistics to determine the number of outside lines required is called traffic engineering. In order for this to make sense, you need to know how many calls of what duration will be handled during the busiest hour of the day. Most people do not have this information, and therefore use judgment combined with trial and error in estimating the number of outside lines needed. In the world of telephone traffic engineering you may hear the term CCS which stands for 100 call seconds (C being the Roman numeral for 100) or, more simply put, 100 seconds worth of telephone calls. 36 CCS or 3600 call seconds are equal to one hour's worth of calls known as an Erlang. The statistical tables or software programs express call volume in this manner The Telecom Handbook 29 THE PBX to determine the number of outside lines needed to handle this volume of calling. Something called grade of service is expressed in terms such as P.01 meaning that, statistically speaking, one percent of all calls will be blocked. Another consideration in planning for the system size is that Voice Mail, paging systems and other peripheral systems also take up ports in the PBX. Additional Considerations On PBX Sizing Each telephone system from each different manufacturer has maximum capacities for both the number of outside lines and desktop telephones it can support. This is determined by the par- ticular design of he manufacturer and has to do with economics as well as technology. Smaller capacity systems with fewer ca- pabilities are sold at lower price points. As an organization grows, they may reach the point where their current system is "maxed out" and needs replacement, enabling the supplier to sell them a new system. The more basic design of these systems also en- ables them to be sold at a lower cost. In general, the larger systems (over 100 telephones) may be more flexible in terms of expan- s

ion, but even so, the cost of expansion can be significant and may involve the change out of both software and circuit boards. If you are considering a system from a particular manufacturer, looking at their entire product line can provide you with insight into their strategy for providing systems to organizations of vary- ing sizes. A few of the larger manufacturers (such as Avaya, formerly Lucent, formerly AT&T and NorTel, formerly called Northern Telecom) provide systems for 5 telephones up to sys- tems with 10,000 telephones or more. While the smaller systems are overall less profitable, there has been a need for the big com- panies to compete with the manufacturers of smaller systems to keep their customer base intact. Most very large organizations have small locations as well, SO for a manufacturer to provide complete coverage, it must of- fer the smaller systems. 30 to The Telecom Handbook CHAPTER 2 Many other manufacturers target a more limited range. There are many more manufacturers of smaller telephone systems (ei- ther PBXs or more basic systems sometimes known as "Key Systems") than of large systems. Only 4-5 companies go up to the 10,000+ telephone sizes. How the PBX Works What Happens to your Voice at the Desktop Your voice is converted to a digital form within the desktop telephone before it is sent over the cable to the PBX in the tele- communications equipment room. The device in the telephone that converts your analog voice into a digital signal is called the codec, which stands for "coder- decoder." It is this same device that converts (or decodes) the digital signals back into the recognizable voice of the person with whom you are speaking. While the PBX and telephones are evolving to a different technology known as IP (Internet Protocol) the codec in the tele- phone is still the device used for translating digital signals into human voice for sending (speaking) and receiving (listening). PCM (Pulse Code Modulation) has traditionally been used in most PBXs that are now slowly making the trans

ition to IP as a protocol for sending the voice signals from one point to an- other in a digital form. The same transition is being made as the voice is sent out over the telecommunications network to the person at the other end as telecommunications service provides change over to IP for transmitting both voice and data. Your Voice Moving through the PBX Once the digitized voice arrives from the telephone into the PBX through the cable within the walls, it remains in the digital form as it moves through the PBX on what is called the digital The Telecom Handbook * 31 THE PBX Pulse Code Modulation (PCM) This is the most common method of encoding an ana- log voice signal into a digital form. First, the amplitude of the voice conversation is sampled. This is called Pulse Amplitude Modulation. This PAM is then coded into a binary number (combination of ones and zeroes). The voice signal can then be transmitted, switched and stored digitally. There are three main benefits to PCM: (1) it is less expensive to transmit a digital signal than an analog signal, (2) by turning an analog signal into a digital sig- nal, it can be interleaved with other digital transmissions such as computer and fax transmissions and (3) a voice signal that is transmitted end to end in a digital form comes through more clearly with less noise than one which is transmitted and switched in the analog form. PCM refers to a technique of digitizing voice and is not a universally accepted standard. The most common PCM method is to sample a voice conversation 8,000 times per second. The theory behind this is if the sam- pling is at least twice the highest frequency on the channel then the result sounds okay. PCM is used to transmit 24 voice conversations over a T-1 circuit. It places 24 voice conversations on two pairs of copper wires. It contains 8,000 frames (logical units of data also called packets) each of 8 bits of 24 voice channels plus one framing bit which equals 1.544 megabits per second, the speed of a T-1. <8000 X (8x24+1) = 1.544 megabits

(1,544,000 bits. A bit is a zero or a one.) - Definition compliments of Newton's Telecom Dictionary it The Telecom Handbook CHAPTER 2 data bus. Each PBX manufacturer uses a proprietary method for transmission both from the telephones and inside the PBX. There- fore it is not possible to use the telephone from one manufacturer with the PBX of another. While it has been anticipated that the transition to IP would eliminate this, it appears that a proprietary telephone that works with the manufacturers specific operating system will be still necessary to access all system capabilities. This enables the PBX manufacturers to hold onto the profitable business of selling desktop telephones to work with their PBXs. Connecting the PBX to the Outside World Through a T-1 In most newer PBXs, there is a T-1 circuit board enabling the T-1 to be delivered right into the PBX where the 24 separate channels of the T-1 are separated enabling the identification and transmission of up to 24 separate conversations. If the PBX is older, or if there is not enough space left in the PBX for a T-1 circuit board, an external device called a channel bank, as men- tioned earlier, can serve the same purpose, separating the channels of the T-1. In this case, the PBX is equipped with trunk circuit boards requiring a separate port in the PBX be used for each of the 24 channels of the T-1 since to the PBX, this looks no differ- ent that 24 separate analog outside lines (also known as trunks). Earlier PBXs and How they Worked Up through the 1960's, many PBXs still in place had a cordboard as the attendant console. If you know where to look (old hotels and apartment buildings, for example,) you still see a few today. The cordboard served the basic functions of allowing the extension user to signal the switchboard operator, enabling the operator to set up a circuit and connecting the extension user to an outside line. From this cordboard comes the term tip and ring. This refers to two separate wires on the plug which, when plugged in, meet with two

contacts in the outlet to complete the circuit. This term is The Telecom Handbook S 33 THE PBX still sometimes used to refer to the wires needed to complete the telecommunications circuit. It may also be used as a term for a POTS (plain old telephone service) line, which is a regular dial tone line. The cordboard was the point at which the control of the switching took place, connecting telephones to outside lines in varying combinations by plugging in cords. This controlled the backroom switching equipment (PBX). As the number of outside lines and telephones grew, along with the need for less reliance on the switchboard operator, newer types of switching systems evolved. These automated the basic operations of the cordboard. This took place in both business locations and telephone company central offices (where cordboards had also been used). Several generations of electro-mechanical switching meth- ods followed. The invention of the transistor permitted the use of electronics within the switch. This device, along with the integrated circuit, provided higher speed and lower cost, using less power. Telephone systems, in both businesses and in the telephone company central office, now resemble computers. The system logic is no longer electro-mechanical, as in the past. It is now controlled by stored instructions in the system memory. In some older sys- tems (1960's, 1970's and early 1980's) there is a physical path set up through the PBX for every call. This is called a space division system. In other systems, the spaces were time-shared by small encoded bits of conversation in what is called time division. Telephone System Design (PBX and Key Systems) The way in which a telephone system is set up is often called the system design. Up until the 1980's, the differences between Key Systems and PBXs were clear. Key systems were for smaller businesses, and their distinguishing characteristic was that each outside line (outside telephone number) appeared on everyone's telephone. 34 30 The Telecom Handbook CHAPTER 2 Key

System Design A typical key system for a small office may be set up in the following manner. When the first line is in use, incoming calls ring on the second line and on down through the sequence of telephone numbers. This is known as the hunt group. It contin- ues until reaching the last line in the group. With all lines in use, the caller hears a busy signal. If the receptionist answers a call, it is put on hold and the called person is told to pick up on line 3. When the button is depressed for the third line at any telephone in the office, the caller is there. Users of the key system press down a key or button of a line to place an outgoing call. They hear the dial tone coming from the local telephone company central office. There is no need to dial 9 to place an outside call. Many key systems are still set up in this manner and are re- ferred to as a square key system (Figure 2.2). This means that every telephone looks the same and picks up the same group of outside lines. This works well in offices where there are no more than ten outside lines. After that, it becomes difficult to remember who is on which line and is confusing for both users and callers left on hold and asked several times, "Who are you holding for?" Figure 2.2 A Square Key System 883 1193 883 1193 883 1193 LINE 3 LINE 3 LINE 3 883 1192 883 1192 883 1192 LINE 2 LINE 2 LINE 2 883 1191 INTCM 1 883 1191 INTCM 2 883 1191 INTCM 3 LINE 1 LINE 1 LINE 1 The Telecom Handbook 35 THE PBX If a company has been operating with a square key system with more than ten lines and it is working well, there may be no need to change if you replace the system. Key systems usually have an intercom SO that the reception- ist can announce a waiting call to the person requested by the caller. The intercom also enables system users to call each other. Key systems typically have more options in terms of internal communications than do PBXs. You may hear that a telephone system is "just a key system," used in a derogatory manner to suggest that it is not as good as PBX

. In fact, most of the key systems currently on the market incorporate many, if not all, of the functions of a PBX, SO the distinction has become blurred. You may see the term hybrid referring to a key system that can be set up either like a square key system or a PBX. When selecting a telephone system, it is more important to focus on the system capabilities for features and growth than on whether it is a hybrid key system or a PBX. PBX Design A PBX has traditionally been set up in the following manner. The organization has a main telephone number, sometimes end- ing in a double or triple zero (for example 635-5300). When this telephone number is busy, the calls roll over to the second line and then on through the hunt group as we described with a square key system. With a PBX, there may be a greater number of outside lines and these lines do not appear on every telephone. Instead, they are answered by a central position known as the switchboard or attendant console. The caller tells the switchboard operator or attendant the name of the person called. "May I please speak to Linda Storaekre?" Then the operator extends the call to that person by dialing an extension number assigned to the called person's telephone. To place an outgoing call, the same group of outside lines is used. Since the person placing the call has only an extension 36 so The Telecom Handbook CHAPTER 2 number on his telephone, it is necessary to press the button for that extension number and dial an access code, usually 9. In doing so, a free outside line is selected and the person can then place a call. If all lines are in use, as with a square key system, callers to the main telephone number hear a busy signal. People trying to place outgoing calls, when dialing 9, will also hear a busy signal (sent from the PBX, not the local telephone com- pany central office) indicating that all lines are in use. It is important to understand that the total number of tele- phone calls in progress, whether they are incoming or outgoing, cannot exceed the t

otal number of outside lines. If you have ten outside lines and receive four telephone calls at the same time as six people are placing outgoing calls, the next caller to your tele- phone number will hear a busy signal. Outside lines are also called telephone numbers, dial tone lines, trunks and POTS lines (plain old telephone service). What we have described above, with all calls coming into a switchboard operator, is a traditional telephone system design (Figure 2.3). With the increasing use of Voice Mail and Auto- mated Attendant, many systems are being set up differently. For example, a type of outside line called a Direct Inward Dial trunk may be used. This allows each person using the system to have a separate telephone number to give to callers SO that their specific extension may be called directly without the intervention of the switchboard operator. If the directly-dialed extension is not an- swered or is busy, the call may then go to the switchboard operator or it may be answered by Voice Mail. The caller hears the voice of the person called. "This is Christine Kern. I'm not at my desk right now, but please leave a message and I will return your call, or dial 0 for immediate assistance." The caller may then leave a message that will, in turn, activate a message waiting indicator on the telephone of the person called (Figure 2.4). An Automated Attendant can take the place of the switch- board operator answering the main telephone number with an announcement such as the following: "Thank you for calling CMP Books. If you know the extension of the person you are calling, The Telecom Handbook * 37 Figure 2.3 Traditional Telephone System Combination Trunks For Incoming And Outgoing Calls Switchboard Attendant Console Local Telephone Co. Central Office Telephone Extensions Incoming Call - A call comes in on a combination trunk and is answered by the switchboard attendant. Caller is then sent to the correct extension. Outgoing Call - Extensions dial 9 to get dial tone from the combination trunk for placing an

outgoing call. Switchboard attendant is usually not involved in this process. Figure 2.4 Telephone System With "DID" Trunks and Voice Mail Combination Trunks For Outgoing Calls Only VOICE MAIL "DID" Trunks For Incoming "This is Beth Cockrell. Calls Only. Every Extension I'm not at my desk Can Be Dialed Directly right now. Please leave From The Outside. me a message and I'll call you back." Local Telephone Co. Central Office Telephone Extensions Incoming Call - In this scenario, calls are placed directly to the telephone extension, bypassing the switchboard attendant. When the extension is unanswered or in use, the calls forward to Voice Mail. Outgoing Call - Extension dials "9" and selects a combination trunk. Figure 2.5 Telephone System With Automated Attendant and Voice Mail Telephone Answered "Thank you for calling. If you know the extension number you may dial it now. For sales, press 1..." AUTOMATED ATTENDANT Telephone Combination Trunks For VOICE MAIL J Unanswered Incoming And Outgoing Calls Local Telephone Co. "This is Rich Laino. I'm not at my Central Office desk right now. Please leave me a message and I'll call you back." Incoming Call - The PBX, Automated Attendant and Voice Mail are housed in the same room and sometimes within the same cabinet. The call movement is controlled by the system software. Callers answered by the Automated Attendant direct their calls to the correct extension. Outgoing Call - Extensions dial "9" to place outgoing calls on combination trunks. CHAPTER 2 please dial it now. To order a book, dial 1; to place advertising, dial 2; for a company directory, dial 3; or please wait for assis- tance." You still need a live person at some point to handle callers who do not know what they want or who do not wish to use the automated system (Figure 2.5). PBX Functions (Also Called Features) Way back when, some enthusiastic PBX salesperson decided to call PBX operating capabilities "features." These are the ca- pabilities that enhance the systems ability for you to process telephone calls

. Answering Position/Attendant Console Every telephone system has what is known as the answering position where a receptionist or switchboard operator has his- torically answered the incoming calls. With a key system, the answering position may look the same as each of the other tele- phones in the system. Most key systems have a separate module which is attached to the telephone at the answering position known as a DSS/BLF or direct station select and busy lamp field. It consists of buttons representing each of the telephones in the system. When a call comes in, the receptionist answers it. He then looks at the BLF. If the lamp is lit next to the button representing the telephone of the called person, the receptionist knows that person is on a call and asks the caller to wait or takes a message. If the lamp is not lit on the BLF, the receptionist depresses the button next to the "busy lamp," which automatically rings the telephone of the called person. This is where the name Direct Station Select comes from. It means that by pressing that button, the station (or telephone) represented by that button is "selected." Some PBXs use the same DSS/BLF concept, but most have what is called the Attendant Console or Switchboard Console as an answering position. There may be more than one attendant The Telecom Handbook $ 41 THE PBX console. Each system has a limit to how many consoles can work with the system. The console is typically much larger and differ- ent in appearance than the telephones. Every telephone system's console works differently, but in general, the calls ring in on ei- ther one or several buttons on the console (sometimes called loop keys), usually accompanied by an audible ring and flashing indi- cator. The attendant presses the button to answer the call. The caller is then "extended" to the appropriate extension number, which the attendant dials on a touch-tone pad on the console. It is typically necessary to hit another button to send the call to the extension after the extension number is dialed. Mos

t consoles also have a display which provides some in- formation such as the calling name or extension (for internal calls) or the PBX trunk number that the call is coming in on. Even with systems that use direct inward dial numbers and voice mail, there is still typically at least one attendant console which also handles calls returning from unanswered telephones, from voice mail and calls from extensions dialing "0". System Features Accessible To The Desktop Telephone Working With A PBX Outgoing Calls Placing a telephone call to an outside location: On most business telephone systems (PBXs) you dial 9, wait for an outside line dial tone, and dial the telephone number. You then hear a ring- ing signal that is sent to you from the local telephone company central office to let you know that the other end has not yet an- swered. You are not hearing the actual ringing of the telephone you have called. On other systems (smaller Key Systems), when you pick up the handset you already have an outside line dial tone and need only dial the telephone number, without dialing 9. Dialing 9 has become an accepted convention. There is not a technical reason that a telephone system cannot be set up to dial a 42 The Telecom Handbook CHAPTER 2 different digit for dialing out, provided it has not been used for any other function. Intra-office Calls and Intercoms Placing a call to another telephone inside the office: Most business telephone systems enable you to reach any other tele- phone on the system by dialing the three- or four-digit extension number of that telephone. The called telephone may ring differ- ently (probably a different cadence) to indicate an intra-office call. The display of the ringing telephone may indicate the name of the person who is calling. There are many different types of business intra-office com- munications. In addition to simply dialing another extension number, most systems have other capabilities sometimes known as intercoms. Some are separate group intercoms for a specific department, or there ma

y be two-way "boss-secretary" inter- coms. The "boss-secretary" intercoms are designed to emulate the older style button and buzzer type intercoms that worked very well. These intercoms took up two buttons on a multi-button tele- phone, one for the buzzer and the other for the intercom path on which the conversation between the boss and the secretary took place. Some intercoms have voice announce which enables the voice of the person who calls you on the intercom to speak to you and you to respond back, without having to lift the handset. Off-hook voice announce (less common) enables someone within your com- pany to speak to you through the speaker of your telephone while you are on an outside call using the handset. Dial intercoms are subgroups within a business telephone sys- tem, enabling members to call each other by dialing one or two digits without having to dial the complete extension number. The call may also ring on a separate button on the telephone, rather than on the button of the main extension number. Some business telephone system intercoms have paging, en- abling an announcement to be made from the speaker of every The Telecom Handbook - 43 THE PBX telephone at the same time (no more than 15 telephones simulta- neously on most systems.). Other systems enable access to a separate overhead paging system. Smaller business telephone systems (Key Systems) tend to have more flexibility in terms of the internal communications options than do the larger systems (PBXs). Incoming Calls Receiving a telephone call from either outside or inside the office: If someone is calling you, you answer by picking up the handset and saying "Hello." Some systems enable you to an- swer by just pressing a speaker button and saying "Hello" without lifting the handset. Other systems enable you to just say "Hello" without touching anything (seldom used but has application in environments where the recipient can't lift the receiver himself). Incoming telephone calls may provide the telephone number or name of the caller with C

aller ID providing your system in equipped to accept and display the number (or name) of the per- son calling. On Hold Putting a call on hold: Many telephones are equipped with a button, often red or orange in color, which enables you to put a call in progress on hold. This means that the call is still at your telephone. The caller cannot hear you, SO you are free to do other things such as call someone else, take another call, search for a file or gather your wits. Multi-line telephones almost always have a hold button. Some single-line telephones have one as well. Some telephones have hold recall, which signals you with a ringing or other sound when you have left someone on hold too long. Other telephones have individual hold, or I-hold. This means that if you put a call on hold at your telephone, no one else in the office that has the same line or extension can take the call off hold from any other telephone. 44 N The Telecom Handbook CHAPTER 2 When a call is on hold, the light on the telephone where the call is holding rhythmically flickers to distinguish it from a call in progress (usually a steady light) or a new ringing call (light flashing on and off). Most systems also provide the ability to distinguish a call you put on hold from a call someone at another telephone put on hold it you both have appearances of the same extensions or outside lines on your telephones. Call Transfer If you wish to send a call to another telephone within your office and the extension the call is on does not appear on that other telephone, you must transfer the call. Most telephones are equipped with a transfer button that you press prior to dialing the extension number to which you want to transfer the call. You announce that you are going to transfer the call to the person at the other extension, and when you hang up, the call is transferred. If you do not announce the call and the extension to which you have sent the call does not answer, the caller may end up back at your desk, at the switchboard or in Voice Mail. This dep

ends upon how the system is programmed. Conference Calls Most telephone systems are equipped with a conference but- ton on the telephone. This enables you to set up a conference among three or more people, connecting people within your of- fice to others outside the office. Systems vary in the number of inside and outside callers that can be conferenced. Typically, it becomes hard to hear on a conference call with more than three participants unless you are using specialized conferencing equip- ment that is separate from the telephone system. For conferences of more than three or four people, it is advis- able to use special conferencing equipment (called a conference bridge) or an outside conferencing service. It is important to know how to drop off one of the conferees from your conference call without ending the call. Not all systems can do this. If you have The Telecom Handbook % 45 THE PBX set up the conference call from your telephone and you hang up, you may disconnect the other call participants. Last Number Redial Many telephones store the telephone number you have just dialed SO that if you reach a busy signal and wish to try again you need only press the last number redial button. On some telephones you do not need to lift the receiver to do this. Press- ing the redial button will activate the speakerphone. Some telephones have a similar feature called save and repeat. This usually takes up two buttons and enables you to place other calls while the telephone still retains the number you want to retry at a later time. Speed Dialing and Automatic Dialing These capabilities enable you to store frequently called tele- phone numbers in your telephone. Then you need only press one or a few buttons rather than dialing the entire telephone number. If you have spare flexible feature buttons on your telephone, these can often be set up to automatically dial a telephone number by pressing just that one button (typically called Automatic Dialing or Autodial). Or there may be a button for speed dial that you press,

followed by a one or two digit code (on the dial pad), which represents the stored number. On many business telephone sys- tems there is station speed dial, specific to a particular telephone, and system speed dial, accessible to authorized telephones throughout the system. If the telephone system requires dialing 9 to dial out, you may have to program the 9 into your speed dial- ing, although some systems have built in intelligence to add it for you. Call Forwarding If you are not going to be at your desk, some telephones en- able you to forward calls to another telephone either within your office or at an outside location. Many systems can forward your 46 The Telecom Handbook CHAPTER 2 calls to different destinations depending upon whether your tele- phone is (1) unanswered or (2) busy, and whether the caller is (3) inside the office or (4) outside. Some telephones are set up with a button that, when depressed, will send your calls directly to Voice Mail if you are not at your desk. This prevents the caller from having to wait for your tele- phone to ring several times before going to Voice Mail. Off-system call forwarding enables you to forward your office telephone to your cell phone or home telephone. Call Pick Up This function enables you to answer another ringing telephone in your office even though the extension number that is ringing does not appear on your telephone. This is usually accomplished by pressing a button on your telephone labeled call pick-up. If you have a display you may see the name of the person whose call you have picked up, which will enable you to answer appro- priately, "Rose Bodin's office," rather than just saying "Hello." Group call pick-up lets you answer any ringing telephone in your pre-selected group. Directed call pick up requires you to know the extension number that is ringing and to dial it after pressing the call pick up button. Privacy In business telephone systems, it is customary for more than one telephone to pick up the same extension number or outside line such as

a secretary's telephone being able to answer the boss' extensions. Privacy prevents someone else who has the same line or extension from inadvertently cutting in on your conversation. If you want to let him in, you may do SO if you have a privacy release button. Not all telephone systems are automatically equipped with the privacy feature. Some systems have automatic privacy, while others require that a separate button on each telephone be activated to ensure privacy. A separate button called privacy release can let a person The Telecom Handbook . 47 THE PBX at another telephone in on a conversation if you want him to join you or listen in. RELEASE Most telephones working with a PBX have a release button. When you press it, the effect is the same as if you hung up the receiver and then lifted it up again. Pressing release disconnects a completed call and gives you back the dial tone to place an- other call. Do NOT DISTURB When the "Do Not Disturb" button is depressed, on most sys- items, you will not receive internal calls or intercom calls. This button often overlaps in function with a button that, when de- pressed, sends callers directly to your Voice Mail box without ringing your telephone. CALL PARK This enables you to ask a caller to wait, place the call in limbo in a numbered "parking place" in the system (the call will no longer appear on your telephone when parked). You can go to any other telephone on the system and retrieve the parked call by dialing the parking place number. This is also used by switchboard attendants who park calls and then an- nounce over the office paging system, "Tom Taylor, dial 23." 23 is the parking code. CALL WAITING OR CAMP-ON If you are on a call and do not have a second extension, a second call may still get though to you using Call Waiting (also called Camp-On in older systems). You will hear a tone indicat- ing a second incoming call and may press a button or the switch- hook to answer the second call without losing the call you're already on. The first caller cannot hear

your conversation with the new caller. 48 - The Telecom Handbook CHAPTER 2 All of the previous capabilities are features of the PBX ac- cessible from the desktop telephone, usually accessed by pressing a specifically programmed button on the telephone, but some- times requiring the dialing of a numeric access code as well. There are also features that have to do with the physical makeup of the telephone itself such as the display and the speak- erphone. See the chapter on The Telephone for a description of these physical characteristics. Expense Control Function of the PBXs Every time a telephone call is made, money is being spent. Many of the PBX functions help an organization to control this expense. Toll Restriction Toll restriction enables you to program the telephone system SO that each extension has what is called a class of service. Each class of service designation enables the extension to call certain areas and restricts it from calling others. The most sophisticated systems can be programmed to restrict the dialing of specific telephone numbers. Others can restrict by area code or by area code and exchange. Figure 2.6 shows a typical scenario. You may also use class of service to give each extension ac- cess to certain system functions and restrict it from using others. You may hear the term six digit toll restriction, meaning that the first six digits dialed (the area code and exchange) can be restricted through programming. Ten digit toll restriction enables you to restrict dialing to a specific telephone number. Automatic Route Selection Most PBXs and some key systems have the capability for ARS (Automatic Route Selection) or LCR (Least Cost Routing), which are essentially the same thing. Many larger telephone The Telecom Handbook 49 THE PBX Figure 2.6 Classes of Service for Toll Restriction (Example) CLASS 0 = Internal Calls Only CLASS 1 = Local Calls Only to 212, 646 and 917 CLASS 2 = Local Calls to 212, 646, 917, 718, and 914 CLASS 3 = Local and Long Distance Calls Within NY Metropolitan Area 212,

646, 917, 718, 914, 203, 860, 516, 972, 908 and 201 CLASS 4 = Local and Long Distance Calls to Continental US CLASS 5 = Local and Long Distance Calls to US and Canada Only CLASS 6 = Unrestricted - Can Call Anywhere in US or International systems have separate outside lines that, when used, will result in a lower cost for certain telephone calls. For example, your company may have a direct line (dedicated line) connecting you to a long distance carrier. When a call has been dialed from your telephone system, the ARS recognizes where the call is going and sends it over the lowest cost route, based upon how the sys- tem has been programmed. In the 1960's, '70's and '80's many companies had WATS lines (Wide Area Telephone Service). WATS lines were separate outside lines enabling calls to be placed at a discounted rate to specific geographic areas within the U.S. (Band 0 through Band 50 = The Telecom Handbook CHAPTER 2 5, as the areas were called.) It was during this period that the ARS was most important. Now the decisions are simpler. Telephone systems without ARS can get around this by assigning access codes to separate groups of outside lines called trunk groups. In this scenario, you may dial 9 for local calls and dial 8 for long distance calls to access a separate group of lines. Call Accounting Most telephone systems also have the capability to provide information on the calls being made through the system. This includes the time the call was placed, the duration of the call and the telephone number dialed. This is called SMDR (Station Mes- sage Detail Recording) output, Call Accounting output, CDR (Call Detail Recording) output, or AIOD (Automatic Identifica- tion of Outward Dialing), an out-of-date term seldom used. It's important to understand that the PBX provides the raw data only. In order to do anything with the data, it must be captured and processed into a usable format. In many organizations, the SMDR output is stored in a buffer device that then is polled by a call accounting system, usually on site

. Call Accounting is usually PC-based. It accepts the call information from the PBX. It then assigns a cost to each call that approximates the true cost of the call and sorts the calls by extension number. The costs for each extension may also be grouped into department reports, often provided to each depart- ment manager. Calls may also be sorted by account codes, numbers associ- ated with certain clients or projects of the company. Thus, a law firm will know how much is being spent on each client and may use the information for billing call charges back to the client. Under these circumstances, the PBX requires the dialing of an account code before each outgoing call is made. The PBX keeps the account code associated with the call and sends this informa- tion to the buffer device. The Telecom Handbook - 51 THE PBX Traffic Study Most PBXs provide information on how the outside lines in the system are being used (call volume on each outside line). This is called a traffic study. Although the call accounting sys- tem is capable of providing a traffic study, it is not always set up to do SO. Instead, the telephone installation and maintenance com- pany is customarily called upon to poll the PBX for a period of time, often a week, to provide the traffic information. When re- questing a traffic study, it is important to be very specific about the information you want and what your objective is. You may have had a new telephone system installed with 20 outside lines for which you are paying $30 each per month (20 X $30. = $600). Now it's a year later and you want to find out if you really need all of those lines. A traffic study runs for one week and tracks all incoming and outgoing calls. The results indicate that at the busiest times of the day, no more than 10 of the lines are ever in use. Being conservative, you decide to leave 15 lines in place and remove the other 5 (5 X $30 = $150), thus saving your company $150 per month. Note: When you remove outside lines, remind your telephone installation and maintenance c

ompany to reduce your mainte- nance cost, since it is often based upon the number of ports used for outside lines. You must also have your telephone system re- programmed SO that it will not be looking for the missing lines when someone dials 9 or, in the case of your DID trunks, when a call comes in. Here's another situation for which you may wish to run a traffic study. Callers to your organization complain that they are reaching a busy signal. The one-week traffic study shows that all 20 outside lines are in use ten percent of the time, confirming that during this time callers cannot reach your company. You or- der 5 more local outside lines from the local telephone company and have them connected to your system by the telephone instal- lation company. You may need to buy an additional circuit board 52 The Telecom Handbook CHAPTER 2 for the system to accommodate these new lines. Several weeks later you run another traffic study that shows that at the busiest times of day, no more than 22 lines are in use. Callers cease to complain about busy signals. The traffic study also measures call volume on T-1 circuits. It's a good idea to have a traffic study run on your telephone system at least once a year. You may negotiate an annual traffic study as a part of your PBX maintenance contract. Or you may learn how to run the traffic study in-house with your call ac- counting system. MAC (Moves and Changes) Many companies spend thousands of dollars moving tele- phones around the office and changing the extensions or features on the telephone. This activity is MAC work (MAC = moves and changes). It can be provided by your telephone installation com- pany. Most PBXs enable you to do some of your own MAC work using a PC with software that makes program changes to the PBX. In some older systems, the changes may be done with a keyboard only or a dumb terminal. For example, two executives are exchanging offices. It is nec- essary to change the extensions appearing on the telephones in each of the offices, on the secretaries'

telephones, and on the telephones of the groups backing up each of the secretaries. If the telephones are all in place, these changes may all be done from the on-site MAC terminal, without calling in the telephone installation company. It is always advisable to inspect the indi- vidual telephones to be sure that the changes took effect and to change the paper labels which most telephones still use. (Note: Some newer systems enable users to take the telephone with them and plug it in in the new office, retaining all of the extensions and features.) Another example of a PBX change which can be made on- site is that of changing the toll restriction on a telephone. Your call accounting system may indicate that a lot of long distance The Telecom Handbook 53 THE PBX calls are being made from the lunchroom telephone. Since em- ployees are permitted to make local calls only, that telephone is now reprogrammed SO that only calls to the local exchange can be made. All other call attempts will be routed to the switch- board attendant. An advantage of having a MAC terminal on site (and some- one in your company trained to use it) is that it will provide you with current information about how your system is programmed. Otherwise, you may be dependent on your telephone installation company or may even need to collect the information manually. MAC terminals may enable you to obtain the following: A list of all extensions in use in your telephone system. A list of all spare (unused) extensions in your telephone system. A list of all outside lines (trunks) in your telephone system. This will be by the trunk number assigned to each outside line in the PBX. It will not provide the actual telephone num- ber assigned to the line by the local telephone company, although there may be a field for this to be manually entered. A company telephone directory listing name, department and extension number. A list of all extensions with their associated class of service, meaning which areas can be called and which system func- tions can be acc

essed. A list of all classes of service in use in the system and what they mean. A list of how each extension is programmed to forward calls under a variety of conditions, including when the extension is busy and when it is not answered. Information on how each of the slots and ports is used in the PBX control cabinet. Identification of spare slots and ports available for expansion. The Telecom Handbook CHAPTER 2 Typical Differences Between Key Systems and PBXs No analog telephones: Most key systems do not provide the capability for an analog telephone. The proprietary telephone that works with the system is the only one that can be con- nected to it. Thus an analog extension on a jack to be used for a fax machine, a separate computer modem or a single line telephone can typically not be provided through a key system. No Automatic Route Selection for Routing of Calls to the Outside Line with the lowest cost for placing calls. Wireless Telephones with a PBX Wireless telephones working with a PBX are based upon ad- junct (separate but connected) controllers that may use analog links to interface to the main PBX. In the future, this will prob- ably not be necessary as distributed base stations that transmit and receive wireless signals will be supported by separate circuit boards which will reside on a shelf in the PBX cabinet. Alloca- tion of the frequency spectrum and standards must still be resolved before the use of wireless PBX extensions becomes widespread in the United States. This is one area where European and Asian organizations may move more quickly since the U.S. regulatory issues do not exist there. Some cellular telephone service providers enable the cell phone to be used as an extension of the PBX while in the office. PBX Disaster Recovery Planning It is also important to plan what to do when things go wrong. Disaster Recovery Planning is the term often used for this activity. A newer term is COB which stands for Continuation of Business. The Telecom Handbook & 55 THE PBX What if the power fails? Many

Find out what to do when the power returns to ensure that your PBX will be up and running quickly. Many systems are installed with redundancy of varying de- grees up to and including having a complete duplicate system standing by. Other types of backup may include two separate sets of out- side lines from two separate telephone company central offices (very costly) or two different long distance carriers. Some organizations use a service known as Switch Redirect available from some telecommunications service providers. In the event of a disaster causing you to vacate your premises, all or some of your direct dial telephone numbers can be rerouted to another location. The most important aspect of disaster recovery planning is to document it and let everyone know how the plan is to be carried out. Periodic testing is also important. It is often surprising to learn that the typical PBX has not changed as dramatically as one might have expected over the past 10-15 years, particularly in terms of how the desktop tele- phone operates. It is true that the inner workings of most PBXs have evolved towards more efficient use of space with higher density circuit boards and improvement in the methods by which signals are transmitted. However, other than perhaps having the Caller ID displayed, the purchaser of a new PBX will not benefit from any new capabilities. Even with the newer systems cur- rently under development, but not yet ready for prime-time, the 56 is The Telecom Handbook CHAPTER 2 benefits to the person using the telephone are minimal or in some cases, regressing. The chapter on Convergence introduces the concept of a softswitch along with some applications with which organizations are experimenting such as Unified Messaging whose usefulness is yet to be demonstrated on a large scale. The Telecom Handbook os 57 Taylor & Francis Taylor & Francis Group http://taylorandfrancis.com CHAPTER 3 Purchasing a PBX Identifying Your Organization's Requirements While identifying your organization's requirements may sound lik

e a straightforward exercise, it is anything but! Here are some of the areas where organizations go wrong, followed by a suggested approach for doing it well. Top 10 (+1) Places To Go Wrong When Planning For And Purchasing A New PBX Here are the areas where organizations most often go wrong in identifying their requirements: 1. Underestimating time & effort Underestimating the time and effort needed to do this. What you might save at the front end will be more than offset by the cost of trying to fix things after the fact, if indeed they can be fixed at all. 2. Ignoring the details of how the current system is configured Failing to develop a complete understanding of how your cur- rent system is configured and how circuits and peripheral systems are connected to it. This often results in not buying sufficient capability and capacity with a new system, then encountering costly additions after the initial system purchase. Do not assume that this information is readily available. Someone who knows the questions to ask and can document the answers in a clear and The Telecom Handbook or 59 PURCHASING A PBX detailed manner needs to lock himself in the telecom equipment room for a day or two with the PBX technician. 3. Not focusing on how your organization is using the cur- rent system While it takes a lot of time to investigate how your organiza- tion is using the functions of the current system, this is time well spent. For example, "How do you transfer calls from one tele- phone to another?" If you only press the transfer button once now to transfer a call and a new system requires that you press it twice, this may be viewed as a step backwards (which it is!). The intercom is another capability that is often overlooked and can lead to disappointment when a new system is installed. Many manufacturers have focused their energy on accommodating "new technology" at the expense of making the system easier to use. 4. Assuming uniform capabilities among manufacturers Assuming that all manufacturers telecommunications system

s pretty much have the same capabilities. They don't. 5. Not completely thinking through Call Coverage Not having enough discussion and documenting how your organization will cover calls under a variety of circumstances. (i.e. when called person not at the desk, when called person is on another call, day, night, weekend, etc.). You may find that you have purchased a system that cannot accommodate your plans. 6. Planning Call Coverage with Too Much Detail before the final system selection. Since each different system (even those from the same manu- facturer) has its own proprietary call coverage capabilities and uses its own terminology, it is a wasted effort to plan call coverage 60 a The Telecom Handbook CHAPTER 3 down to the details of every telephone at every desktop. Trying to change it after the fact can result in a cumbersome call cover- age set up that results in poor service to callers and staff. 7. Not communicating your requirements well to the suppliers Collecting a lot of good information, but failing to communi- cate it well to the telecommunications system suppliers bidding on your project. It is suggested that this communication be both in writing and in a lengthy discussion to confirm what is in writ- ing, to avoid misunderstandings when it is too late to do anything about them. 8. Falling in Love with Technology Failing to balance a desire for experimentation with new tech- nology with the need for traditional reliability. 9. Ignoring the Telephone at the desktop Paying too little attention to the telephone instrument that will sit on everyone's desk while focusing on technology and backroom equipment. Most people judge the system by how well they like the telephone. 10. Not Budgeting Enough Not budgeting a sufficient amount of money for the purchase, including a variety of professional services skills needed to imple- ment it such as consultants, system designers, programmers, project managers and trainers. 11. Spending too much Not understanding how much the system will cost, what is needed and

what is negotiable. Therefore many organizations spend up to 100% more than is required. The Telecom Handbook " 61 PURCHASING A PBX Identifying the Requirements Why Do You Need a New PBX? First of all, be very clear why you are going to buy a new system. Valid reasons may include: System Out-of Date and Difficult to Arrange for Maintenance Your PBX is SO old that it can no longer be maintained prop- erly. This may mean that all the technicians capable of working on the system have retired. Or it may mean that the manufacturer is not longer making replacement parts for the system. Be sure that both of these "facts" have been carefully researched, as they are seldom the case. Most telephone systems, though aging, can be supported indefinitely buy finding the right resources. One company now even advertises that it specializes in the support of "vintage telephone systems." Few of these PBXs installed. Maintenance support unavailable One can make a good case for not being the first one on your block to purchase a particular new telecommunications system, either from a familiar or a new manufacturer. If few organiza- tions buy the system and it is not a commercial success, you may be stuck with an unsupportable system that is not very old. For example, Avaya (formerly called Lucent. Lucent was for- merly called AT&T) used the name Merlin for several different systems. Avaya also came out with the System 25 and then dis- continued it several years later, SO although there are still some System 25s around, the companies who maintain them are few and the cost of maintaining them can be high. System at its Maximum Capacity As PBXs reach their maximum capacities, particularly if they have not been efficiently maintained, they tend to not operate as well as they had in the past. Problems arise, such as callers being 62 The Telecom Handbook CHAPTER 3 lost when transferred. Also every system does have a maximum capacity beyond which it cannot expand. You may need the capacity because you are adding people or you may need it

to because to wish to add capability to your system such as voice mail or networking with other locations. System lacking in desired capabilities Before you buy an entire new system for a certain capability, make sure that there is no other alternative and that you really need this capability. Some older PBXs cannot display the tele- phone number of the person who is calling you from the outside (Caller ID) on your telephone. This is one function that organi- zations may replace the system to obtain. Often a system upgrade, while it may include the purchase of hardware and software, will be less costly than purchasing an entire new system. System problems that cannot be resolved Replacing a system to solve problems without knowing what is causing them never makes sense. The same problems may be there after the system is replaced since they may have been a result of (1) poor system design, which you may have inadvert- ently replicated (2) outside line problems (3) cabling problems or (4) power problems, to name a few. Before replacing a system, it is important that the problems have been identified and it is agreed that they cannot be fixed. This often takes patience, money and skill on the part of who- ever is diagnosing the problem. At worst, it may take a technician, an administrator, an engineer and a consultant. At the end of the process, the outcome may point to one of the other reasons for replacement such as the system being too old to maintain or at maximum capacity. Or if the problem is not with the system, then a considerable expense may have been avoided. Poor experience with the maintenance company It is always advisable to purchase a PBX that can be sup- ported by a number of different companies in your area. This The Telecom Handbook - 63 PURCHASING A PBX way, if service is not satisfactory, you have options. Some orga- nizations are forced to replace the PBX if no such option exists. A PBX Request For Proposal (with sample questions) Whether you are upgrading an existing system or purchasing a new

system, put it in writing. This gives you a better chance of getting what you need and avoiding misunderstandings. It also provides a basis for comparing systems. Here is an excerpt from a written description of a telephone system. There are also sample questions from a Request for Pro- posal used for one of our clients at DIgby 4 Group, Inc. We believe that technical specifications should be accompanied by clear En- glish (or whatever your language is) descriptions of how you, the client, want things to work. Description of the Telephone System Operation Incoming calls from outside callers will ring into the system in one of several ways. A caller dials the main telephone number 212-883-0000, which is answered by the switchboard attendant and extended to the requested person. There will be two switchboard con- soles, but sometimes only one will be in operation. A caller dials a direct inward dial number, which rings di- rectly to the telephone of the person dialed. Each telephone, except for telephones in common areas, will have a direct inward dial number. A caller dials 212-983-0000, which is the first of four sepa- rate outside lines (not direct inward dial) that appear on the telephones in a customer service department. Note: The following describes what is known as Call Cover- age. This means, "How are we going to be sure the telephones 64 & The Telecom Handbook CHAPTER 3 are answered?" If a person is not at the desk when the telephone rings, the call can be covered in one of several ways. Answered by another person who has a direct appearance of that extension on their telephone. Live coverage is a key ob- jective, SO coverage of this type will be widespread. Answered by another person who has depressed his call pick- up button to answer the ringing telephone, although he has no direct appearance of that ringing extension. The display on the telephone of the person answering the call will indi- cate the name of the person for whom the call was originally intended, SO that the call can be answered appropria

tely. Answered by another person to whom the call has been for- warded by the person who is not at the desk. Answered by the switchboard attendant. Our objective is to have most calls handled at the department level rather than returning to the switchboard console. Unanswered intra-office calls are forwarded to Voice Mail that will enable the caller to leave a recorded message. Anyone answering a call, including the switchboard atten- dant, will be able to offer the caller the option of leaving a message in the Voice Mailbox of the person being called. The caller will then hear the personal greeting of the person being called and will leave a message. All telephones will have the capability to send unanswered calls to Voice Mail. This will be done by each user before leav- ing the desk, by depressing a button on the telephone. This button may also work to enable redirecting of incoming calls when the extension is busy. The capability to automatically forward calls from unan- swered and busy telephones into Voice Mail must be a part of the system, although we may elect not to use the system in this man- ner at the outset. The Telecom Handbook e 65 PURCHASING A PBX If a person is busy on another call, an incoming call can be covered in several ways: The call can "roll over" to another extension which appears on the same telephone and rings simultaneously on one or more other telephones. Please let us know if there is a limit to the number of multiple appearances of an extension. Once the call has rolled over, it can be answered by another person by depressing the call pick up button, although there may be no appearance of that extension on his telephone. Answered by another person to whom the call has been for- warded by the person at the busy telephone. Answered by the switchboard attendant, although, as stated above, it is our intent to have a minimal amount of callers return to the switchboard. Intra-office calls to a busy extension can be answered by Voice Mail, giving the caller the option of leaving an auto-

mated message. Any caller reaching Voice Mail will have the option of reach- ing a live attendant by holding on at any point in the process. Instructions for escaping from Voice Mail by dialing 0 are in- cluded as a part of the system. Outgoing calls will be made by dialing 9 to access a group of combination trunks or a T-1 for long distance calling. Automatic route selection in the system will select the lowest cost circuit for placing the call. Internal calls will be made on the system intercom by: (1) dialing a three or four digit extension, (2) on a separate group intercom or (3) on a boss-secretary type of intercom. All three types must be available and work when the person called on the intercom is on an outside call. Most telephones in the system will be multi-line with a dis- play. The display will have the ability to indicate the name of the person who is calling on internal calls and the source of the call 66 de The Telecom Handbook CHAPTER 3 (trunk identification by type and telephone number assignment - 7 digit) for incoming outside calls. It will also display the name and number of the outside calling party, when available. Required System Capabilities The following capabilities are required for the proposed sys- tem to be considered. Please state in your response whether each capability is standard, optional or not available in the proposed system. (Note: This list was prioritized for our particular client.) 1. Capability to obtain a traffic study, on demand, indicat- ing use on the T-1s and other trunks carrying incoming and outgoing calls. Also must be able to track recalls to the switchboard from unanswered and busy extensions and internal calls. 2. Capability to make system changes on-site such as relo- cating telephones (to cabled, system activated locations), changing extension appearances or system forwarding. 3. Capability for incoming calls to forward in four different directions for internal/busy, internal/no answer, external/ busy and external/no answer. 4. Capability to accept an ISDN PR

I type of circuit. 5. Capability to integrate with an Interactive Voice Re- sponse system. 6. Station and system speed dialing capability (state num- ber per station). 7. Built-in speakerphone capability on multi-line telephones. 8. Conferencing of up to five people. This must include the capability to drop calls to a busy or unanswered telephone from a conference call already in progress. The Telecom Handbook 36 67 PURCHASING A PBX 9. Differentiated ringing for internal and outside calls and for different telephones within the same area. 10. Toll restriction and the capability to override it. 11. Last number redial. 12. Capability to provide both boss-secretary and dial inter- coms, which can signal another telephone while it is in use with an audible tone distinguishable from the regular ringing telephone. Desirable System Capabilities Please state in your response whether each capability is stan- dard, optional or not available in the proposed system. 1. Capability to generate a printed directory of extension users. 2. Capability to provide some Automatic Call Distribution (ACD)-like reports as an indicator of staff productivity, such as the number of calls handled by each extension and the duration of the calls. 3. Capability to recognize Caller ID and ANI information sent to the PBX from the central office. 4. Capability to retain Caller ID or ANI digits with a call that is transferred or a call coming through the Auto- mated Attendant. 5. Capability for off-hook voice announcement on the intercom. 6. Capability to set up a busy lamp field for the switchboard attendant console and for individual multi-line telephones. 7. Toll fraud security features on the PBX and Voice Mail systems. 68 & The Telecom Handbook CHAPTER 3 Please provide the maximum for the following: Number of times the same extension can appear on other telephones. Number of extensions in a call pick up group. Number of call pick up groups in the system. Number of times a call can forward when the original exten- sion is unanswered or busy. Nu

mber of forwards for which the original destination of the call or the Caller ID will continue to appear on the display of the ringing telephone. Number of buttons on each telephone instrument proposed which can be used for extension appearances. Number of speed dial numbers per telephone and system wide. Number of participant capacity on a conference call. Number of ports for each type of circuit board proposed. Number of spare slots in the cabinet as proposed. Number of ports for telephones and outside lines in the pro- posed system at its maximum capacity. Number of seconds for the set-up of an outgoing call. System Specifications Please base your pricing on the following requirements: One digital PBX. Two T-1/PRI circuit board for each 24 DID (direct inward dial) and both-way trunks. The Telecom Handbook $ 69 PURCHASING A PBX One T-1/PRI circuit board for access to a long distance carrier. Growth capacity in cabinet for a third T-1/PRI 20 Combination trunks (growth capacity in cabinet to 60) Two attendant consoles with DSS/Busy lamp field. 250 Multi-line digital display telephones with a minimum of ten buttons which can be programmed for line appearances and system feature access (Note: Line Appearance refers to a button on which a PBX extension is located) 50 Multi-line digital display telephones with a minimum of twenty buttons which can be programmed for line appear- ances and system feature access 8 Digital single line telephones Growth capacity in cabinet to add 40 multi-line telephones One system administration terminal and printer A call back modem to prevent unauthorized access into the remote maintenance port One Voice Mail system integrated with the proposed PBX. - 8 ports (Growth capacity in cabinet to 16 ports) One Voice Mail system administration terminal and printer (Please state if the same terminal and printer can be used for PBX system administration) For the above-described system, provide a total price and the components, showing how the price was computed. Once we have agreed upon the exte

nt of recabling or reuse of existing cabling, please provide a separate price for all cabling related work, separating materials from labor. 70 The Telecom Handbook CHAPTER 3 Provide Optional Pricing for the Following 4 and 8 hour battery back-up. Back-up to maintain DID trunks on the T-1/PRI in the event of a power failure. A PC-based Call Accounting system to work with the pro- posed PBX (including hardware and software). Please mention any toll fraud detection capability of your PBX or Call Accounting system. Additional Information Requested 1. Add-on pricing for all system components including sta- tions, circuit boards and additional cabinets. Note: The term Add-on is used to refer to any addition of equip- ment to an original purchase agreement. Maximum capacity of PBX - in existing cabinet, and with additional cabinets. 3. Maximum capacity of Voice Mail - in existing cabinet, and with additional cabinets. 4. Number of hours of memory in the Voice Mail system as proposed. 5. Is a two-way speakerphone on the multi-line display tele- phones standard or optional? If optional - what is the cost? 6. How many pairs of wires does the proposed multi-line telephone require? 7. With your proposal, please include copies of your stan- dard purchase and maintenance contracts. 8. Please enclose a picture of the proposed telephone sta- tions and attendant console. The Telecom Handbook 12 71 PURCHASING A PBX 9. Please provide a description of the intercom options with the proposed system and of exactly how they are oper- ated by the extension user. 10. Is the proposed Voice Mail system capable of incorporat- ing remote fax retrieval capability? If so, please explain how this is accomplished. 11. Does your installation price include all coordination required with the telecommunications service providers? Please describe your procedures for providing this support. 12. Does your installation price include training? Please pro- vide detail of the scope of training provided. 13. Does your maintenance agreement include support o

f the Call Accounting and telecommunications management software, including a hotline for customer questions? 14. Does your pricing consider any "trade in" on the ex- listing PBX? 15. Does your company sell and support Video Teleconfer- encing equipment? If so, please describe these capabilities. 16. Are the handsets in the proposed system hearing aid- com- patible? Can a TDD (Telephone Device for the Deaf) be used to call to and from the proposed system? 17. Please provide a list of at least ten customers using the proposed system (same release for PBX and Voice Mail and same system administration software for PBX). Maintenance Support Requirements 1. Two-hour emergency response and 24-hour standard re- sponse is a requirement. 72 %> The Telecom Handbook CHAPTER 3 2. The proposed system must have remote diagnostic capa- bility. Please explain your procedure for monitoring the system performance remotely. Can the remote point be deactivated by the customer to prevent unauthor- ized access? 3. Please provide the point of dispatch for your re- pair technicians. 4. Does your company reduce the cost of the maintenance agreement if the customer agrees to provide coordination of repairs with the local and long distance carriers? The above is considered to be a brief Request for Proposal document. Some are much more detailed, particularly for larger systems with more than 200 telephones. The purpose of includ- ing it here is to give you an idea of some of the questions to ask and the level of detail required to purchase a telephone system. The Telecom Handbook - 73 Taylor & Francis Taylor & Francis Group http://taylorandfrancis.com CHAPTER 4 Your Call Center Telephone System - The ACD An ACD or Automatic Call Distributor is a specialized type of PBX. It is typically used in what is known as an Incoming Call Center, although outgoing calls are made through it, too. When you call to make an airline reservation or to order some- thing to be delivered by mail, your call is likely being answered by an ACD. You may hear the n

ow familiar recorded announce- ment, "All representatives are busy with other customers, your call will be answered by the next available representative." Characteristics that distinguish an ACD from a regular PBX are: Calls are answered by the representative who was idle the longest. The call volume and workload can be monitored in real-time. Callers are queued up and answered in the order that they are received. Statistics are available on the level of customer service pro- vided and the productivity of the representatives answering the calls. Most business telephone systems are designed to have more telephones than outside lines, the assumption being that not everybody is going to be on the telephone at the same time. For example, you may have 100 people sharing 25 outside lines. In an ACD environment, it may be just the opposite. A smaller group of people handle a greater number of lines, assuming that callers will wait for some period of time for the "next available representative." With an ACD, 25 The Telecom Handbook 75 THE ACD people may be handling 100 outside lines. This affects the system components and software, distinguishing an ACD from a regular PBX. As with PBXs, every ACD works in a different way. No two are exactly alike. Some companies manufacture telephone systems to work specifically as an ACD and not as a regular office telephone sys- tem. Their systems are known as stand-alone ACDs. Most other PBX manufacturers have ACD capabilities that may be purchased as an option, at considerable additional cost (can add 50% to 100% to the price). A PBX can be set up to work exclusively as an ACD. You may also have an ACD as a sub- system of an office PBX, but not have all telephones working in the ACD environment. The Collins Division of Rockwell pioneered the ACD in the early 1970's with an installation at Continental Airlines and later at Pan Am and United Airlines. The system evenly distributed large volumes of incoming calls for reservations and ticketing. This bit of history was contributed by Pau

l Lutz of Rockwell. The Call Center environment has been one of the first to ex- periment with the integration of telephones and computers. In many Call Centers, when your call is answered by a representa- tive, a computer screen of information about you pops up. This is called a screen pop. ACD Hardware The ACD is put together in the same manner as the PBX. There is a control cabinet that holds printed circuit boards. There are separate circuit boards for different types of outside lines and other circuit boards controlling the telephone instruments. The system can expand in the same manner as a conventional PBX. Some newer ACDs are server based and may look like a PC. Some manufacturers provide different telephones for the ACD agents (agents are also called Custom Service Reps or TSRs/ 76 The Telecom Handbook CHAPTER 4 Telephone Service Reps). These telephones usually have a dis- play providing information such as how many calls are waiting to be answered. An ACD telephone may also be equipped with a headset, since the calls tend to come in one after another. This makes it cumbersome to keep picking up the handset. The head- set also keeps the agent's hands free to retrieve and enter computer-based information using the computer keyboard. The buttons of the agent telephone itself are different from regular PBX telephones. The telephone is typically set up SO that only one call at a time can be answered by each representative. Therefore only one extension number will appear. There may be another separate button used for outgoing calls. Note: An ACD is probably not the right choice if your environment requires cus- tomer service representatives to juggle multiple calls on hold. Other buttons on the telephone may enable the representa- tive to log on or log off the ACD system. When the agent is logged off, no calls will be sent to that telephone. As in other areas of telecommunications, there is a lot of ter- minology unique to ACDs. The queue, for example, refers to the group of callers waiting (lined up in order

, controlled by soft- ware) to be answered. Abandon rate is another favorite, measuring the length of time after which callers tire of waiting in queue and hang up. As mentioned above, telephone service representatives in a Call Center are often called TSRs or agents. ACD System Features Here are some of the system features you may find on an ACD: Routing INBOUND CALL ROUTING The heart of any inbound Call Center operation is Inbound Call Routing. There are two phases of inbound call routing: routing to a group, and then routing to a specific agent within The Telecom Handbook 77 THE ACD a group. Inbound Call Routing uses intelligent programming to recognize and accommodate Call Center traffic and agent per- formance. The system may have the flexibility to: Anticipate changing traffic and performance patterns, re- spond to unanticipated changes in traffic or agent performance and play announcements at any point. Route callers to voice processing devices such as IVRs, Fax Servers or Voice Mail equipment, always providing the caller the option to return to his place in queue. Recognize priority callers. Advise callers of the number of callers ahead of them or anticipated time before they will be answered. Put a pause in inbound routing until some predefined event occurs or some period of time passes. Queue calls to multiple groups simultaneously, including groups at re- mote centers and agents at home. Permit supervisor, administrator or management to make changes as needed. Most Call Centers try to distribute calls evenly among all agents within a group. However, there are instances where some agents are better prepared than others. For example, when new agents are added to a more experienced group, management wants the better-qualified agents to handle more calls than the new agents. Several different schemes can be used for selecting an agent within a group: 1. Top down/bottom up 2. Longest idle 3. Agent priority (based on experience or skill set) 4. A combination of longest idle and agent priority 5. Performance

Parameters & Thresholds 78 The Telecom Handbook CHAPTER 4 SKILLS BASED ROUTING In some incoming call centers, instead of routing the callers to the agent who has been idle the longest, routing is affected by the agent skills required to handle the call. Callers can be sent to the agent best qualified to help them, according to a set of pre- defined parameters. The caller's needs can be determined by what number he called, what number he is calling from or what option he selected from an automated announcement menu presented to him before being sent to an agent. If a caller waits too long for a specifically skilled agent to be available, the system may be pro- grammed to send him to a less qualified person, rather than waiting indefinitely. Skills based routing is routinely used in Help Desk Call centers where callers are looking for help with the operation of software programs. The ACD attempts to route the caller to the agent most skilled in the program with which they need help. OVERFLOW Overflow is a feature that recognizes when agents in one group are backlogged, then reroutes calls to another group that may have fewer calls waiting. In the best implementations, the call volume/performance analysis is done automatically and continu- ally in real time, freeing supervisors and management personnel from minute-by-minute monitoring of each groups call volume. NIGHT SERVICE The majority of Call Centers, including those that work a 24- hour day, notice a significant difference in traffic between normal office hours and the night shift. If the center is open at all, it may rely more on automated response systems and will have fewer agents in place to handle calls. Predefined inbound call routing schemes must be modified to accommodate the late hours environment. An intelligent Call Center system shifts to a night service inbound routing scheme based on time of day. Individual super- visors may also invoke night service manually. When invoked, calls may be routed to another inbound routing scheme, to an an- swering d

evice, another location or callers may just hear ringing. The Telecom Handbook * 79 THE ACD DEFLECTION The cost of calls to an 800 number mounts rapidly as callers wait for an agent to answer. To decrease the cost of callers waiting in queue for an answer, deflection decreases hold times by having callers reach a busy signal or by rout- ing the calls to another destination. This happens when the system recognizes that a management-defined threshold has been reached. Deflection is typically based on the number of calls in queue. A more effective parameter offered by some systems is "time in queue." In this case, a caller receives a busy signal when the longest call in queue has been in queue over "X" minutes or seconds as defined by management. INTERFLOW This provides automatic transparent traffic rerouting based on predefined times/days or traffic thresholds. This is useful for multi-site Call Center networks where call volumes and hold times may be high in one location while there is idle time at another location. Or a business may span several time zones and man- agement may want to avoid overtime in one zone by routing calls to another location. Interflow helps Call Centers attain optimum agent productivity while controlling toll costs. Performance Measurement To be successful, Call Center management must set perfor- mance objectives, and then measure performance against these parameters. Real time displays and historical reports should show actual performance as compared to these criteria. A list of per- formance objectives might include average: Time to answer Talk time Hold time Work time Idle time Time in queue 80 The Telecom Handbook CHAPTER 4 Agent Capabilities Sign-On/Off Agents may serve more than one group and may rotate among several workstations during a shift or during a week. In order to monitor and evaluate agent performance, it is impor- tant to be able to track which agent is at which telephone. Each time agents make a change, they are asked to sign on and sign off the group they are serving. A

utomatic sign on/off processes save time and prevent abuse of the system. Using screen-based software programs, supervisors may also move agents from one group to another. ID/Password Agents may sign on using an identification number, with or without a password. The ID and password should be viable from any agent workstation, freeing agents to work at any desk during any shift. When agents serve multiple groups, tracking require- ments will determine whether or not the agent uses the same or different ID and password for each group served. Auto Answer/Auto Release Automatic Answer and Automatic Release are features fre- quently used together and in conjunction with headset operations. With Auto Answer, agents receive calls without lifting a handset or depressing a button on the telephone. Agents may be alerted to the incoming call with a ring, beep, message, zip tone or other indicator. Auto release terminates the call when the local or long distance carrier disconnects. Thus, the agent is immediately freed to move on to other activities such as follow-up paperwork or receiving the next call. This feature also prevents agents from adding seconds or minutes to each call by delaying release. Auto release serves as a productivity tool for the agent and as an anti- abuse measure for management. The Telecom Handbook * 81 THE ACD Call Alert Work conditions in a busy Call Center would be unbearable if all telephones rang with every incoming call. Silent room con- ditions (where telephones do not have an audible ring) improve morale and productivity. Alternative means of alerting agents to incoming calls include: Audible ring, ring-beep, zip tone (sounds a like a zipper be- ing opened quickly, heard only by the agent) for agents with a headset. A brief announcement, which may relate to call origin or may prompt the agent for a unique greeting. Also used for agents with a headset. Visible indicator such as a flashing lamp or phone display, typically with incoming line or caller information. Wrap/Work Call Center managers

must be careful to balance pressure for agent productivity against increasing agent stress and frustration. Wrap and Work are features that allow the agents some period of time between calls to complete call-related paperwork. Management may predefine the wrap period, or may allow agents to invoke Wrap as needed. Work is a similar feature, allowing agents time to complete call-related tasks. Unlike Wrap, Work is not an automatic fea- ture. Agents place themselves in and out of Work as needed. While some systems may combine these two features, they should be defined and reported/displayed separately for better evaluation of agent performance. Transaction Code In addition to any database information agents may enter into the caller's profile, there may be a need to collect other call- related information. For example, agents may collect information 82 * The Telecom Handbook CHAPTER 4 on "method of payment," "how caller heard about the company or offering", etc. This information may be used for specific re- ports to evaluate marketing activities, meet accounting requirements, etc. Agents are able to enter transaction codes at any time during or after the call. Codes should be flexible, allowing for multiple fields, and should provide a display SO that the agent can verify the input before completing the data. Emergency Record Some Call Centers are susceptible to harassing or threaten- ing calls. It's important to be able to document these calls without alerting the caller. Agents should be able to immediately confer- ence-in a centralized recording device as soon as they recognize a call of this type. Supervisor Alert When agents receive threatening, harassing or other problem calls (difficult question, hostile caller) they may need supervi- sory assistance. With Supervisor Alert, agents are able to get their supervisor's attention without interrupting the call in progress. Supervisor Alert may have these features: Transparent to caller. Alerts designated supervisor; then, if not available, hunts for first available

supervisor in management-de- fined sequence. Informs supervisor of agent calling and reason for the alert. Calls in Queue Display Agents need to balance providing polite and friendly ser- vice against the need to answer as many calls as possible. A "calls in queue display" notifies agents if there are any calls The Telecom Handbook 83 THE ACD waiting, and alerts them if the queue builds beyond a manage- ment-specified threshold. Thus, agents are prompted to shorten calls during busier periods. Agent Statistics Display Typically, when agents are able to monitor their own per- formance they become more productive. Agent station sets can provide immediate feedback for agents who want to evalu- ate their own productivity. Some of the statistics that might be displayed include: Time on line (since signing in) Number of Call Center calls handled (inbound/outbound) Average time to answer Average talk time Time in wrap/work idle time (time between calls) Number of non-Call Center calls Agent at Home Just as management may want to send calls to remote Call Centers, they may want to send calls to individual agent homes or small storefront locations. This capability is particularly applicable for accommodating employees with special needs. In addition, it may be useful in disaster recovery situations. The work at home solution should be nearly transparent for both agents and supervisors, meaning they have the same fea- tures, regardless of location. Supervisor Capabilities Supervisor Agent Features Supervisors may have the option of serving as agents. Super- visor stations may be able to support all agent features in addition to supervisory features from one telephone. 84 - The Telecom Handbook CHAPTER 4 Real Time Displays Supervisors are responsible for ensuring high agent pro- ductivity without sacrificing quality service. The supervisor's most important tool for accomplishing this task is the set of real-time screen-based displays of agent and group perfor- mance provided. To be most effective, these displays may be col

or coded and presented in either tabular or graphic formats as a user selected option. Displays may show real-time status as well as historical information. Groupings Any one supervisor may typically be responsible for 10-15 agents, even though the entire group serving a particular func- tion may be much larger. Supervisors may be able to identify agent information for their specific agents without scrolling through the entire group display. Similarly, supervisors may be able to display a subset of agents from several different groups, if necessary (for example, in evaluating trainees throughout the Call Center). This super group/ sub group capability is very im- portant in larger Call Centers. Reports In addition to real time information used for daily supervi- sory functions, historical reports are necessary. These identify trends and are vital to planning. Reports may include information about individual agent and group performance, trunk usage, transaction codes, emergency recording and alerts. In addition to standard reports, systems may permit supervisors or administrators to develop custom reports, unique to their own Call Center requirements. Raw data is stored for some management-defined period of time, and is available for additional reports for a period of at least a week, up to one or more years. The Telecom Handbook 30 85 THE ACD Monitoring Displays and reports tell only part of the story of agent per- formance. To really evaluate agent performance and to assess the quality of service provided, supervisors must be able to listen to agents in actual telephone conversation with callers. This has traditionally been accompanied by a supervisor walking to the agent's desk and listening to the call by plugging a second head- set into the station set. This approach has become an accepted part of Call Center culture for many organizations. However, the same result can be achieved with silent and split/silent monitor. Silent monitor allows the supervisor to listen, undetected, to both the agent and the caller

. If necessary, the supervisor may join the call as an active participant at any time. Split/ silent monitor allows the supervisor to listen, undetected to both the agent and caller, but if necessary, the supervisor may prompt the agent and remain undetected by the caller. This is particularly useful in training situations, or where threatening or harassing calls are anticipated. Typically silent monitor is invoked on demand, or it may be timed, or it may rotate through the group as calls are terminated. Forced Answer When supervisors notice that the number of calls in queue is rising, they may wish to artificially improve the average time to answer (decrease caller time waiting in queue) by forc- ing agents to answer new calls as soon as prior calls are terminated. This is done by forcing a group-wide override of the wrap/work features. In the past, supervisors watched Call Center traffic, then physically moved agents to the groups that were most active. Today, it is no longer necessary to move the agent to the call. The Telecom Handbook CHAPTER 4 Sophisticated, intelligent systems now bring the calls to the agents. Nevertheless, Call Center supervisors want to retain the option of moving agents between groups should the need arise. Thus, systems offer an agent Move command that al- lows agents to be moved even while busy on an incoming/ outbound call. At the end of the call, that call's statistics ap- ply to the original group. Then the agent should get his or her next call from the new group. Messaging When supervisors walked around the Call Center to monitor agent activity, they could easily stop and speak to any agent at any time. Now that Call Center systems have eliminated the need to actually go to the agent's work station, supervisors must find a new way to "talk" with their agents: hence, supervisor-to-agent messaging. Supervisors can send text messages to agent telephone displays. These messages may be predefined: "Good job!" or "Waiting time down 15 minutes" or may be created as needed. Alternatively,

the supervisor may be authorized to send messages using a wall mounted display unit. Unlike display phone mes- saging, the wall-mounted display message is visible to everyone in the viewing area. Caller Support Capabilities Automated Data Collection This is the ability for callers to use touch-tone signals (or the spoken word) to obtain answers to predefined database inquiries such as account status, balance due, driving directions, etc. Au- tomated inquiry requires an IVR (interactive voice response) system which may be integrated with other functions such as Automated Data Collection and/or Voice Messaging. It prompts a caller to respond to specific questions either us- ing the spoken word or touch-tones. Frequently used in after-hours The Telecom Handbook no 87 THE ACD retail catalog sales or to report service problems in a support cen- ter, this feature may be referred to as voice forms. Intelligent Queuing This provides an announcement to the caller stating the esti- mated time he will have to wait before the call is answered. Frequently the anticipated hold time announcement feature is combined with an option to leave a message, rather than wait for an agent. Instead of estimating the waiting time, the caller may be told how many calls are ahead of him. Request Callback This feature allows the carrier to request a callback. This op- tion may be provided in conjunction with the "anticipated hold time" announcement feature, or may be implemented as an op- tion during inbound call routing. Agent Voice Mail Permits the caller to leave a message rather than waiting to speak with an agent. Depending on the system, the message may be directed to a group of agents or to a specific agent. This op- tion may be presented at one or more times while the caller is in queue holding for an agent. Voice Mail as part of a standalone ACD may not incorporate all of the functions of standard Voice Mail. Be sure you're clear in defining your expectations when purchasing a system. Network Services (Outside Lines) for ACDs There

are a variety of network services (outside lines and their capabilities) that can be used to expedite Call Cen- ter ACD function. 88 & The Telecom Handbook CHAPTER 4 Any type of outside line that works in a PBX can work in an ACD including T1/PRI, combination trunks and DID trunks. The number and type of outside lines to order is an important part of the overall system design and depends upon call vol- ume, service level objectives and number of customer service representatives. Traffic engineering tables for Call Center ACDs use dif- ferent parameters than for PBXs to how many outside lines are needed. Network based services often used in call centers to route the calls include DNIS and ANI. DNIS (Dialed Number Identification Service): Many sepa- rate 800-type toll-free telephone numbers may share an "800" trunk group. DNIS allows the receiving Call Center equip- ment to recognize the digits the caller dialed, and base inbound call routing accordingly. The digits dialed may be translated to a "reason called" and displayed for the agent, prompting an appropriate greeting. ANI (Automatic Number Identification): In some locations, the telephone number from which the incoming call is placed can be recognized by the Call Center equipment. This can then be used for inbound call routing or for an automated database access. A similar function to ANI known as Caller ID, also delivers the calling telephone number. Other Call Center Capabilities Predictive Dialing Many Call Centers are designed to both take incoming calls and place outgoing calls. The same group of agents may be re- sponsible for both sales and collections. The sales calls are primarily incoming, and the collections calls are placed during lulls in incoming traffic. The Telecom Handbook * 89 THE ACD Outbound calls may be placed automatically using predic- tive dialers. Predictive dialers analyze incoming call traffic and agent activity, then automatically place outgoing calls when agents are about to be available. These predictive dialers help manage- ment