5 Functional entities

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

5.1 General

5.2 WIC (WebRTC IMS Client)

A WebRTC IMS Client (WIC) establishing the service control signalling path over W2 interface, that is compliant with this specification shall implement the role of WIC capabilities defined in subclause 6.2, subclause 7.2 and subclause 8.2.

Where SIP over websockets is used, as specified in RFC 7118 [2], and no alternative SIP profiles have been agreed between the operator of the eP-CSCF and the operator of the WWSF, then the SIP used by the WIC over the W2 reference point shall conform to the requirements for UE over the Gm reference point as specified in 3GPP TS 24.229 [3].

When the WebSocket protocol is used, the WIC shall act as a WebSocket Client, as defined in RFC 6455 [24].

The SDP used shall conform to the requirements for UE over the Gm reference point as specified in 3GPP TS 24.229 [3] and further specified in the present document.

5.3 WWSF (WebRTC Web Server Function)

The WebRTC Web Server Function (WWSF) is the initial point of contact in the Web that controls access to the IMS communications services for the WIC as specified in 3GPP TS 23.228 [4].

5.4 WAF (WebRTC Authorisation Function)

The WebRTC Authorisation Function (WAF) issues authorization tokens that are provided to the WIC via the WWSF as specified in 3GPP TS 23.228 [4] and 3GPP TS 33.203 [9].

NOTE: The WWSF and the WAF realisations can be physically co-located or physically separate.

5.5 eP-CSCF (P-CSCF enhanced for WebRTC)

For the Mw reference point, the eP-CSCF shall conform to the requirements for the P-CSCF as specified in 3GPP TS 24.229 [3].

Where SIP over websockets is used, as specified in RFC 7118 [2], and no alternative SIP profile have been agreed between the operator of the eP-CSCF and the operator of the WWSF, then the SIP used by the eP-CSCF over the W2 reference point shall conform to the requirements for P-CSCF over the Gm reference point as specified in 3GPP TS 24.229 [3].

The SDP used by the eP-CSCF over the W2 reference point shall conform to the requirements for UE over the Gm reference point as specified in 3GPP TS 24.229 [3] and further specified in the present document.

5.6 eIMS-AGW (IMS Access Gateway enhanced for WebRTC)

The functionality of the eIMS-AGW is specified in 3GPP TS 23.228 [4] and in 3GPP TS 23.334 [13].