I.2 Overall architecture

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

Figure I.1 presents a high-level architecture diagram showing how Border Control Functions fit into the IMS architecture.

Figure I.1: Border Control Functions

The Mx reference point allows S‑CSCF/I‑CSCF/P‑CSCF/MSC Server enhanced for ICS or MSC Server enhanced for SRVCC to communicate with an IBCF in order to provide border control functions. The functionality of the reference point is specified in TS 24.229 [10a].

The Mm reference point allows IBCF to be the entry / exit point towards other IM Core Network Subsystems and provide border control functions. The Ici reference point allows IBCF to be the entry / exit point towards other SIP networks and provide border control functions. The functionality of the reference points are specified in TS 24.229 [10a].

The Ix reference point allows the IBCF to control the TrGW. The functionality of Ix is defined in TS 29.162 [75].