Information technology - Telecommunications and information exchange between systems - Corporate telecommunication networks - Tunnelling of QSIG over SIP
|Publication Date:||1 April 2009|
|ICS Code (Telephone networks):||33.040.35|
This International Standard specifies tunnelling of "QSIG" over the Session Initiation Protocol (SIP) within a corporate telecommunication network (CN). "QSIG" is a signalling protocol that operates between Private Integrated services Network eXchanges (PINX) within a Private Integrated Services Network (PISN). A PISN provides circuit-switched basic services and supplementary services to its users. QSIG is specified in Standards, in particular  (call control in support of basic services),  (generic functional protocol for the support of supplementary services) and a number of Standards specifying individual supplementary services. SIP is an application layer protocol for establishing, terminating and modifying multimedia sessions. It is typically carried over IP , . Telephone calls are considered as a type of multimedia session where just audio is exchanged. SIP is defined in . Often a CN comprises both PISNs employing QSIG and IP networks employing SIP. A call can originate at a user connected to a PISN and terminate at a user connected to an IP network or vice versa. In either case, a gateway provides interworking between QSIG and SIP at the boundary between the PISN and the IP network. Basic call interworking at a gateway is specified in . Another case is where a call originates at a user connected to a PISN, traverses an IP network using SIP, and terminates at a user connected to another (or another part of the same) PISN. This document addresses this last case in a way that preserves all QSIG capabilities across the IP network. It achieves this by tunnelling QSIG messages within SIP requests and responses in the context of a SIP dialog. The tunnelling of QSIG through a public IP network employing SIP is outside the scope of this specification. However, the functionality specified in this specification is in principle applicable to such a scenario when deployed in conjunction with other relevant functionality (e.g., address translation, security functions, etc.). This specification is applicable to any interworking unit that can act as a gateway between a PISN employing QSIG and a corporate IP network employing SIP, with QSIG tunnelled within SIP requests and responses.