3GPP Work Item description

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

Feature:     Enhancements to the Cx and Sh interfaces

The specification of the Cx and Sh interfaces are important elements of the IP Multimedia Subsystem. 

The Cx interface is the interface:
        between the Home Subscriber Server (HSS) and the Call/Session Control Function (CSCF)

The Sh interface is the interface:
        between the Home Subscriber Server (HSS) and the SIP Application Server (SIP-AS), and 
        between the Home Subscriber Server (HSS) and the OSA Service Capability Server (OSA SCS). 

The Home Subscriber Server (HSS) is the master database for a given user containing the subscription-related information to support the network entities actually handling calls/sessions. 

During the specification of these interfaces for Rel-5, it was intended that a Diameter Multimedia Application would be used, but due to time constraints and resource limitations, this IETF specified application could not be used and the Cx and Sh specifications directly specified their immediate requirements. This was done with concessions from the IETF on the use of Diameter command codes. The intention with this work item is to enhance the Cx and Sh specifications to fulfil the IMS Stage-2 and Stage-3 enhancements, retaining backwards compatibility with the existing Release 5 specifications.  This is also to be the basis for the new IETF work on a Diameter Multimedia Application. 

Work to be led by N4.