Information technology — Telecommunications and information exchange between systems — Private Integrated Services Network (PISN) — Mapping functions for the tunnelling of QSIG through H.323 networks
ISO/IEC 23290:2004 specifies functions for using an H.323 packet network in order to interconnect two Private Integrated services Network eXchanges (PINXs) forming part of a Private Integrated Services Network (PISN). Interconnection is achieved by carrying the inter-PINX signalling protocol over the H.323 call signalling channel, making use of the protocol tunnelling facilities of H.323, and inter-PINX user information (e.g. voice) over logical channels established through H.323. Each logical channel usually represents a unidirectional media stream conveyed by means of the Real-time Transport Protocol (RTP). The inter-PINX signalling protocol is assumed to be QSIG, as specified in ISO/IEC 11572, ISO/IEC 11582 and other International Standards.
ISO/IEC 23290:2004 provides for an on-demand type of interconnection, where a separate H.323 call is established at the start of each PISN call and cleared down at the end of that call. A semi-permanent scenario where a single H.323 call with an indefinite lifetime carries QSIG on behalf of many PISN calls is described as an additional option.
In the scenarios covered in ISO/IEC 23290:2004, the PINXs participating in a call are not necessarily aware of the H.323 network providing the interconnection, and the features available are those of the QSIG network. This is different from a scenario where true interworking between QSIG and H.323 (i.e. QSIG-H.323-QSIG) is used to connect two PISNs or two parts of the same PISN. In this latter case, all networks participate in a call on equal terms, and features are limited to those available in all networks and supported by the gateways. This latter scenario is outside the scope of this document.
ISO/IEC 23290:2004 is applicable to PINXs that can be interconnected to form a PISN using QSIG as the inter-PINX signalling protocol.
