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.