5 Functional entities

24.3373GPPIP Multimedia (IM) Core Network (CN) subsystem IP Multimedia Subsystem (IMS) inter-UE transferRelease 17Stage 3TS

5.1 Introduction

This clause associates the functional entities with the inter-UE transfer roles described in the stage 2 architecture document (see 3GPP TS 23.237 [4]).

5.2 User Equipment (UE)

If the SC UE supports the Controller UE procedures for IUT transfer then the SC UE may include the g.3gpp.iut-controller media feature tag as described in annex B in the Contact header of SIP requests and SIP responses.

To be compliant with inter-UE transfer in this document, a UE shall implement the role of an SC UE:

– by following the procedures specified in 3GPP TS 24.229 [7] for registration of the UE in the IM CN subsystem; and

– dependent on the desired functionality, one or more of the procedures according to subclause 9.2, subclause 10.2, subclause 11.2, subclause 12.2, subclause 13.2, subclause 14.2, subclause 15.2, subclause 16.2, subclause 17.2, subclause 18.2, subclause 19.2, subclause 20.2, subclause 21.2, subclause 22.2, subclause 23.2 and subclause 24.2.

NOTE: In the inter-UE transfer, a session can be collaborative session where there are one controller UE and severeal controllee UEs. The controllee UE can be a legacy UE and does not have be compliant with the above subclauses.

5.3 Application Server (AS)

To be compliant with inter-UE transfer in this document, an AS shall implement the role of an SCC AS according to subclause 9.3, subclause 10.3, subclause 11.3, subclause 12.3, subclause 13.3, subclause 14.3, subclause 15.3, subclause 16.3, subclause 17.3, subclause 18.3, subclause 19.3, subclause 20.3, subclause 21.3, subclause 22.3, subclause 23.3 and subclause 24.3.