The electronic version of this International Standard can be downloaded from the ISO/IEC Information Technology Task Force (ITTF) web site.

ISO/IEC TR 21890:2001 The purpose of this Technical Report is to investigate the interoperability of Private Integrated Services Networks (PISNs) and Internet Protocol (IP) networks, with a view to identifying possible scenarios for interoperation, problems that will have to be solved if particular scenarios are to be pursued further, and possible future standardization activities in this area. In particular, the following aspects of interoperability are investigated:
- the interworking of PISNs and IP networks via a gateway;
- the connection of PISN components via IP networks.
For each of the above, aspects considered include architecture, addressing (including use of IP addressing), services, protocols, security, quality of service and mobility. This is conducted within the context of leading standards for voice and multimedia communication over IP networks, including ITU-T recommendation H.323, IETF Session Initiation Protocol (SIP) and ITU-T recommendation H.248.
Possible future standardization activities resulting from this Technical Report can include work items relating to IP networks and work items relating to PISNs, as well as work items concerned specifically with interoperability.
The dominant traffic in PISNs is voice, and therefore this Technical Report focuses on interoperability considerations for voice traffic. However, many of the standards that support voice in an IP network are also applicable to multi-media traffic (e.g., voice, video and data). Although in many respects similar to voice, fax traffic has slightly different requirements and is not explicitly considered in this Technical Report. It could be the subject of further study.