1. Field of the Invention
This invention relates to a method and apparatus for providing a single service destination in a telecommunications network. In particular, but not exclusively, the invention relates to the provision of a single mailbox for multi-service users having access to a plurality of different telephony services.
2. Description of the Related Technology
Known voicemail systems allow a calling party to leave a message for a called party when the called party is unable or unwilling to answer the call. If a call is not answered by the called party, the calling party is directed to a local messaging system or a remote messaging centre where the calling party may record a message for subsequent retrieval by the called party. Such systems are known in both fixed and mobile telephone networks and also in data networks such as the Internet.
FIG. 1 shows a prior art telecommunications network. The telecommunications network includes a Public Switched Telephone Network (PSTN) 102 to which a telephone 100 (telephone A) is connected and which is connected to a service provider network 104. Service provider network 104 includes a local telephone exchange switch 110 which serves a telephone 106 (telephone B). The user of telephone B has a voice messaging service provided by the service provider who operates service provider network 104. The voice messaging service is implemented via a messaging centre 108 (MCB) which is connected to local telephone exchange switch 110. Operation of messaging centre 108 is under the control of the service provider of network 104.
FIG. 2 is a flow diagram according to the prior art which illustrates the steps involved in a user of telephone A leaving a voice message for the user of telephone B, for an arrangement in which the user of telephone B has a voice messaging service provided by the service provider who operates network 104 (shown by annotation 200 in FIG. 2).
When telephone A is used to make a call to telephone B, the telephone dialing number for telephone B is dialed. This initiates a call that is routed via PSTN 102 to local telephone exchange switch 110 which serves telephone B located in service provider network 104. The call initiation results in a signaling message (shown by step 2a) traversing PSTN 102 which contains a calling line identifier (CLI) (also referred to as a caller ID) for telephone A (denoted CLI: A) and destination dialing number for telephone B (denoted DN: B). When local telephone exchange switch 110 receives the signaling message of step 2a, it rings telephone B as shown by step 2b. 
In this case, the user of telephone B has subscribed to CLI services and the user of telephone A has not withheld their CLI when making the call, so the signaling message of step 2b contains a CLI for telephone A.
If telephone B is not answered and the user of telephone A wishes to leave a voicemail message for the user of telephone B, then after a pre-configured delay, local telephone exchange switch 110 forwards the call to messaging centre 108. The signaling message which is sent to messaging centre 108 (shown by step 2c) contains the originating CLI for the call (denoted CLI: A) and a destination dialing number for messaging centre B (denoted DN: MCB). The signaling message of step 2c also contains a redirecting number, which in this case is the number of the line forwarding the call to messaging centre 108. The redirecting number allows messaging centre 108 to identify in which mailbox to deposit the voicemail message from the user of telephone A: in this case telephone B's mailbox.
FIG. 3 is a flow diagram according to the prior art which illustrates a user of telephone B retrieving a voice message from their mailbox using telephone B. The user of telephone B has a voice messaging service provided by the service provider who operates service provider network 104 (shown by annotation 300 in FIG. 3).
To retrieve their voicemail messages, the user of telephone B calls messaging centre 108, shown by step 3a. This may be done by dialing a short code associated with the messaging centre. A short code may be a three digit short code such as 121, 123 or 901 on UK mobile networks, whereas in US mobile networks, a user may dial their own mobile number from their mobile telephone, which is then forwarded to the messaging centre as their mobile telephone is engaged. Alternatively, the user can dial the full telephone dialing number of messaging centre 108.
The signaling message for step 3a contains a CLI for telephone B (denoted CLI: B) and a destination dialing number for the messaging centre (denoted DN: MCB). Messaging centre 108 checks the CLI of the incoming call, and routes the caller to the appropriate mailbox, i.e. that of the user of telephone B. The user can then either listen to their messages, or, if the system is so configured, may have to enter a Personal Identification Number (PIN) first to prevent unauthorised access to their mailbox.
FIG. 4 is a flow diagram according to the prior art which illustrates a user of telephone B retrieving a voice message from their mailbox. The user of telephone B has a voice messaging service provided by the service provider who operates service provider network 104 (shown by annotation 402 in FIG. 4). In this case, the user retrieves their voice message from a telephone D (see annotation 400) which is different to telephone B.
To retrieve their voicemail messages, the user of telephone B calls messaging centre 108 from telephone D. To retrieve voicemail messages from a telephone different to the telephone B, the user dials the full telephone number of messaging centre 108 that hosts their mailbox which causes a signaling message to be sent to messaging centre 108 in step 4a. 
The signaling message for step 4a contains a CLI for telephone D (denoted CLI: D) and a destination dialing number for the messaging centre (denoted DN: MCB). Messaging centre 108 checks the CLI of the incoming call, but does not recognize it as it identifies a telephone foreign to their service, i.e. telephone D. Messaging centre 108 therefore cannot connect the user directly to their voice mailbox. Instead, messaging centre 108 prompts the user to enter the number of the phone which has a mailbox on that messaging centre, i.e. that of telephone B, and then asks for the user's PIN to authorise access.
The above prior art systems which allow voicemail to be left in mailboxes by calling parties are adequate when a user has a single telephony service. However, if a user has more than one telephone service, for example a mobile telephony service and a landline telephony service, then the user has to deal with different mailbox services hosted by each of the different service providers. This can be impractical for the user as they have to coordinate the messages left in their different mailboxes. Further, the user has to deal with different access methods, different access codes and different user interfaces for the different mailbox services, which can lead to an inefficient use of the user's time and may lead to increased costs if each of the mailbox services must be paid for individually.
The above prior art methods for retrieving voicemail from a mailbox have a problem in that, if a user wishes to retrieve mail from their mailbox using a telephone service not provided by the same provider as who provides their mailbox service, then it is either not possible for the user to gain such access, or the user must enter a full telephone dialing number associated with the relevant mailbox service. This can be time consuming for the user, and especially inconvenient if the appropriate number is not readily to hand.
U.S. Pat. No. 7,023,967 relates to a system for sharing voice messaging support which includes a voice messaging system coupled to a wireless network and a wireline network. A mailbox can be shared between telephones on each of the different networks. In order to implement this prior art system, each of the wireline and wireless telephony services must be configured to incorporate the shared mailbox functionality.
It would therefore be desirable to provide improved mailbox services for multi-service users who have access to a plurality of telephony services. A single mailbox for the multiple telephony services would be beneficial, since it would facilitate efficient access methods, both for calling parties leaving messages in the mailbox and for subsequent retrieval of the messages by the multi-service users. Further, it would be desirable to provide such mailbox services with a minimum of reconfiguration and disruption to the existing telephony services and telephony devices.