TISPAN; NGN Release 1; Endorsement of 3GPP TS 29.162 Interworking between IM CN Sub-system and IP networks
The present document describes the interworking between the TISPAN IMS and an external IP network including other IMS networks for IP multimedia service support.
The present document addresses the areas of control and user plane interworking through the network functions, which include the IBCF and I-BGF. For the specification of control plane interworking, the interworking between IMS SIP and an external SIP profile are detailed in terms of the procedures required for the support of both IMS originated and terminated SIP sessions.
In particular, the present document describes the protocol mappings for support of communications between networks using different IP versions or between networks with NATs operating at their border.