TISPAN; Multimedia Telephony with PSTN/ISDN simulation services
The present document defines the requirements for multimedia telephony services which may be supported by a TISPAN NGN. These requirements form the basis for the definition of network capabilities.
An important aspect of the Multimedia Telephony with PSTN/ISDN Simulation service is to provide PSTN/ISDN like services. Nevertheless the requirements are independent of the media that is used during the communication.
The present document covers part of the transition from PSTN/ISDN to an NGN. Interconnection between the existing networks and a TISPAN NGN is also covered.
The present document only provides requirements for services using IMS. Services provided by a TISPAN NGN to support legacy terminals and interfaces (PSTN/ISDN emulation) are defined in existing PSTN/ISDN documents. Requirements for PSTN/ISDN Emulation are out the scope of the present document and are described in other documents.
New NGN services are out the scope of the present document and are described in other documents. The applicability of PSTN/ISDN simulation services to services other than Multimedia Telephony (e.g. instant messaging) is not defined. Some PSTN/ISDN simulation services (for example communication waiting) are clearly not applicable to some real-time communication services.
The requirements in the present document are described from the user point of view to assist in the transition of phone services to IP multimedia services with a similar behaviour. The requirements do not take into account capabilities of existing protocols. The evolution or modifications to these protocols are beyond the scope of the present document.