TISPAN; Videotelephony over NGN Service Description
The present document defines the requirements for a videotelephony service which may be supported by a TISPAN NGN. These requirements form the basis for the definition of network capabilities.
The present document provides interoperability service requirements for interconnection between existing networks and a TISPAN NGN, and between TISPAN NGN.
The present document only provides requirements for IP multimedia based networks. 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 of scope of the present document and are described in other documents.
The applicability of PSTN/ISDN simulation services to the videotelephony service requirements are defined in the present document.
The requirements in the present document are described from the user point of view. The requirements do not take into account capabilities of existing protocols defined for the IMS. The evolution or modifications to these protocols are beyond the scope of the present document.
NOTE: The present document uses the term "NGN" only in the context of TISPAN.