Under certain circumstances, and with appropriate authorization, law enforcement agencies (LEA) are permitted to legally intercept and monitor communications between individuals that may be targets of an investigation. A common technique, known as wiretapping, involves intercepting telephonic communications between individuals by “tapping” into the communication.
Plain old telephone systems (POTS) and early wireless communication systems incorporating, Class 4 or Class 5 exchanges, a Mobile Switching Center (MSC) and the like, employ circuit switching techniques to connect a calling party to a called party via a communication network. The call is completed upon successfully establishing the circuit between the parties, and the circuit becomes a dedicated link between the parties for carrying on the telephonic communications. All voice communication between the parties is then carried on this circuit.
To provide surveillance, or wiretapping, in such circuit switched systems required only determining and “tapping” the circuit at an appropriate location along the circuit. A circuit is dedicated to the call, and because all of the communications are carried on this circuit, the LEA can be assured of intercepting the entire communication, including in-band and out-of-band call signaling, between the individuals under surveillance from this one tap.
Evolution of communications technology will render obsolete the circuit switched network for both voice and data communication networks. In fact, circuit switched networks are being replaced by packet-based communication networks. In packet-based networks, the information carried by the network, for example data or encoded voice, is organized into packets, and the network carries these packets from the sending party to the receiving party. Within the network there is no single path or “circuit” that carries the packets from the sending party to the receiving party. Instead, the network may be considered a fabric of links, switches and routers that carry packets in an efficient manner. Packets associated with the communications of a first party with a second party may travel on any number of paths. This arrangement of the packet based communication network permits more efficient utilization of communication resources, and hence, permits the communication network to carry more information, with greater stability. Thus, the packet based communication network can service a greater number of users communicating greater amounts of information, i.e., both voice and data.
The Communications Assistance for Law Enforcement Act of 1994 (CALEA) requires that all US based wireline, cellular and broadband personal communication services (PCS) carriers provide the capability of legal, undetectable, bearer and call signaling intercept to law enforcement agencies for any subscriber utilizing their network. CALEA implementation, which is governed by Federal Communication Commission (FCC) regulations, must be completed by Jun. 30, 2000 for non-packet-based networks and by Sep. 30, 2001 for packet-based networks. While the FCC has specified the required functionality, it has not specified or recommended architecture for achieving compliance with its regulations.
As described above in connection with circuit-based, or non-packet-based networks, providing surveillance capability generally requires only determining the particular circuit established for a communication, and intercepting both the bearer and call signaling information carried on that circuit. However, in packet-based networks no single circuit or path carries the data packets which include the bearer and call signaling information. To ensure complete surveillance, it is necessary to ensure that all packets associated with a communication are identified regardless of the path assigned to any particular packet.
Additionally, the FCC regulations specify certain functional requirements beyond bearer and call signaling intercept that must be met for compliance with the CALEA legislation. The regulations are completely set forth in the interim standard J-STD-025, available from the Federal Communication Commission, 445 12th Street S.W., Washington, D.C., 20554. Among these requirements are a capability to provide: content of subject-initiated conference calls, party hold, join, drop on conference call, in-band and out-of-band signaling, timing information, dialed digit extraction, and no interruption of call performance, billing, etc. as a result of CALEA implementation.
Thus, there is a need for a communication network and method that includes surveillance capability and which utilizes packet switched data techniques for providing communication services.