6A Deregistration

24.3713GPPProtocol specificationRelease 16Stage 3TSWeb Real-Time Communications (WebRTC) access to the IP Multimedia (IM) Core Network (CN) subsystem (IMS)

6A.1 General

This clause specifies procedures that are related to deregistration in the IM CN subsystem that are required for support of WebRTC.

The WIC and the eP-CSCF using Gm shall follow the deregistration procedures as described in 3GPP TS 24.229 [3] and the procedures as described in this document in addition. For the WIC and the eP-CSCF using Gm, the appropriate signalling protocol is defined in 3GPP TS 24.229 [3] and this document.

For the WIC and eP-CSCF using non-Gm or non-SIP, the deregistration procedures and the signalling protocol are out of scope of this document.

6A.2 WIC (WebRTC IMS Client)

It is assumed that the WIC has previously registered, and the signalling protocol between the WIC and the eP-CSCF applies SIP over WebSockets where the SIP procedures conform to the definitions for SIP on the Gm reference point as specified in 3GPP TS 24.229 [3].

The WIC shall follow the deregistration procedures speicifed in 3GPP TS 24.229 [3] subclause 5.1.1.6 and subclause 5.1.1.7.

If the WIC have no more public user identities registered in the IM CN subsystem, the WebSockets connection between the WIC and the eP-CSCF shall be removed.

6A.3 eP-CSCF (P-CSCF enhanced for WebRTC)

The eP-CSCF shall follow the deregistration procedures speicifed in 3GPP TS 24.229 [3] subclause 5.2.5.1 and subclause 5.2.5.2.

NOTE: In the scenario that individual public user identity is assigned by the WWSF or the WAF from a pool of public user identities, as an implementation specific option, when the public user identity has been deregistered in the IM CN subsystem, the eP-CSCF can indicate to the WAF that a certain public user identity can be re-assigned, while the procedures for the interface between the eP-CSCF and the WAF is out of scope of this specification.