4.26 Support for Business Trunking

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

An IMS network may support business trunking for IP‑PBXs in two different modes.

– 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 in same manner as an ordinary subscriber.

In static mode, the IP‑PBX does not perform any registration procedures.

Description on the support for IP‑PBX business trunking is provided in Annex S and TS 24.525 [81]. The support for business trunking in static mode is provided by either an IBCF or a P‑CSCF and clarified in Annex S.