3GPP Work Item description

This page contains informal descriptive text only.  See master WID page for further details.

Feature: Multimedia interworking between IMS and CS networks

Within UMTS, the capability of IP-based multimedia (IM) services will enable the support of basic multimedia calls to and from circuit switched (CS) networks (i.e. PSTN, ISDN and GSM/UMTS CS networks). These multimedia calls will require interworking functions within the IM CN subsystem.

The UMTS architecture includes media gateway (MGW) functionality for interworking between the GGSN Gi reference point and CS networks for the user plane, and Media Gateway Control Function (MGCF) and Signalling Gateway (SGW) functionality to allow interworking between the Call Session Control Function (CSCF) and CS networks in the control plan.

This WI will outline the solutions and functionality required within the MGW to deliver the user plane aspects between IM CN subsystems and CS networks for support of basic multimedia calls. Also, it will outline the solutions and functionality required within the MGCF and SGW to deliver the control plane aspects between IM CN subsystems and CS networks to support basic multimedia calls.

The objective of this work item is to address the issue of interworking between the IM CN subsystem and CS networks, in order to support basic multimedia calls.

A significant goal is to define the functionality of the MGW, together with aspects of the MGCF and SGW for the support of multimedia calls to and from CS networks (i.e. PSTN, ISDN and GSM/UMTS CS networks).

The work item will address the issue of control plane interworking (for example, the mapping required between 3GPP profile of SIP and ISUP/BICC, SDP, 324M control protocols, if required) to enable the IM CN subsystem to communicate with CS networks, in order to support basic multimedia calls.

The work item will address the issue of user plane interworking (for example, between the AMR codec used in the IM CN subsystem and possibly other codec types used in CS networks) in order to support basic multimedia calls.

The areas addressed should encompass the transport protocol, transcoding and signalling issues for negotiation and mapping of bearer capabilities and QoS information.

A feasibility study will be performed as a preliminary step to study all implications of the user and control plane interworking.