S.1 General

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

This annex describes the IMS architecture and procedures for support of IP‑PBX business trunking.

Two different modes of operation are supported

– Registration mode, or

– Static mode.

In both modes, the IP‑PBX can be provisioned as a subscriber in the HSS.

In registration mode, the IP‑PBX registers to and receives service from the IMS network as specified in TS 24.525 [81].

The architecture and procedures for an IP- PBX using static mode is described in clause S.2.