"The present document specifies network requirements in terms of service-related capabilities for TISPAN NGN. The present document places requirements for all TISPAN NGN Release 1 subsystems. The present document provides generic requirements for services and interoperability in TISPAN NGN 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. Requirements on service independent subsystems are contained within the service-related subsystem requirements. 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 that are used to determine the network architecture@ requirements and control protocols for a network interface to a customer environment. NOTE: The present document uses the term ""NGN"" only in the context of TISPAN."