ETSI TS 122 401-2008 数字蜂窝通讯系统(阶段2+).通用移动通信系统(UMTS).电信和互联网融合业务和协议(TISPAN).建立在下一代网络技术之上的视频电话业务描述
Digital cellular telecommunications system (Phase 2+); Universal Mobile Telecommunications System (UMTS); 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.