4.4 Signalling concepts

23.2283GPPIP Multimedia Subsystem (IMS)Release 18Stage 2TS

A Single session control between the UE and CSCF:

– For Multi-Media type services delivered via the IP‑CAN within this architecture, a single session control protocol shall be used between the user equipment UE and the CSCF (over the Gm reference point).

Protocols over the Gm reference point :

– The single protocol applied between the UE and CSCF (over the Gm reference point) within this architecture will be based on SIP (as defined by IETF RFC 3261 [12], other relevant IETF RFC’s, and additional enhancements required to support 3GPP’s needs).

A Single session control on the Mw, Mm, Mg, Mi, Mj, Mk, Mx:

– A single session control protocol shall be used on the session control interfaces between:

– MGCF and CSCF (Mg),

– between CSCFs (Mw),

– between a CSCF/IMS ALG and external IP networks (Mm),

– between CSCF and BGCF (Mi),

– between BGCF and MGCF (Mj),

– between BGCF/IMS ALG and BGCF (Mk), and

– between BGCF/CSCF and IBCF (Mx).

Protocols for the Mw, Mm, Mg, Mi, Mj, Mk, Mx:

– The single session control protocol applied to these interfaces will be based on SIP (as defined by IETF RFC 3261 [12], other relevant IETF RFC’s, and additional enhancements required to support 3GPP´s needs).

UNI vs. NNI session control :

– The SIP based signalling interactions between CN elements may be different than SIP based signalling between the UE and the CSCF.

Based on operator preference, border control functions may be applied between two IM CN subsystem networks or between an IM CN subsystem network and other SIP based multimedia network, see clause 4.14 and Annex I for details.

Restrict access from external networks :

– The signalling solution shall allow the operator to restrict access from external networks (application level).

Access to HSS :

– A network operator can control access to the HSS.