Access signalling - Q.2931 and related standards

This paper provides a brief description of the International Telecommunications Union (ITU-T) specified access signalling protocol Q.2931 and the supporting layer 2 signalling ATM adaptation layer (SAAL) that provides the release I signalling mechanism Digital Signalling System No 2 (DSS2). In addition to identifying the functions that are required to be incorporated in a signalling protocol to support call/connection establishment, in-call control and clear-down for a basic point-to-point call, the extensions required for a point-to-multipoint call are also considered The paper then considers further extensions that have been produced to enable the negotiation, modification and look-ahead in relation to the connection in order to provide the capability set 2 step I DSS2 signalling mechanism. In conclusion, a simple road map to the DSSZ ITU-T standards is provided.