The present document specifies the requirements that need to be fulfilled by NGN technical specifications to provide services in an NGN. The present document considers one service set: IP Multimedia Services. Other service sets and generic network requirements to support service deployment and interoperability, are contained in ETSI TS 181 005 [11]. The present document provides generic requirements on networks from a services point of view. Specific details of individual services and capabilities are provided in other documents.

The present document specifies network requirements in terms of service-related capabilities for a TISPAN NGN incorporating an IMS. The present document places requirements for TISPAN NGN Release 1 subsystems. The present document provides generic requirements for services and interoperability in a TISPAN NGN incorporating an IMS in terms of the capabilities for a network or networks. Requirements on service-related subsystems provide sufficient detail for architecture, networking requirements and protocols to be specified. Specific service requirements may be contained in other documents, as identified in the present document, and by other documents referencing the present document. The present document does not define services, only capabilities and requirements. The present document does not place requirements on terminals or other customer-owned equipment. The present document specifies the service-related requirements on an IMS that are used to determine the network architecture, requirements and control protocols for a network interface to a customer environment.