4 Overview of IP Multimedia (IM) Core Network (CN) subsystem inter-UE transfer

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

4.1 General

Inter-UE transfer provides the capability of transferring the communication sessions with multiple media across different UEs and is part of Service Continuity (SC) as described in 3GPP TS 23.237 [4].

Inter-UE transfer does not apply to emergency calls as described in 3GPP TS 24.229 [7].

Inter-UE transfer is an optional part of SC.

The following procedures are provided within this document:

– procedures for UE discovery for inter-UE transfer are specified in clause 9;

– procedures for inter-UE transfer without establishment of collaborative session are specified in clause 10;

– procedures for collaborative session establishment for inter-UE transfer are specified in clause 11;

NOTE 1: The procedures in clause 11 are related to scenarios in which the collaborative session is set up by the controller UE when an end-to-end session already has been established with the remote UE.

– procedures for media transfer within collaborative session for inter-UE transfer are specified in clause 12;

– procedures for release of collaborative session for inter-UE transfer in clause 13;

– procedures for addition and deletion of media with collaborative session for inter-UE transfer in clause 14;

– procedures for session discovery in clause 15;

– procedures for collaborative sessions of participants of different subscriptions are specified in clause 16;

– procedures for establishment of collaborative sessions during session setup are specified in clause 17;

NOTE 2: The procedures in clause 17 are related to scenarios in which the collaborative session and the session towards the remote UE are set up in parallel.

– procedures for assignment and transfer of control of a collaborative session are specified in clause 18;

– procedures for media flow transfer within a collaborative session are specified in clause 19;

– procedures for session replication / media replication performed by the SCC AS are specified in clause 20;

– procedures for session replication / media replication performed by the remote UE are specified in clause 21;

– procedures for collaborative session handling upon loss of collaborative session are specified in clause 22;

– procedures for collaborative session media modification are specified in clause 23; and

– procedures for service continuity and MMTEL interactions are specified in clause 24.

Inter-UE transfer procedures are not limited by amount of established sessions.

4.2 Underlying network capabilities

Inter-UE transfer assumes the use of a number of underlying network capabilities:

1) provision by the home network operator of SCC AS on the IM CN subsystem, as specified in 3GPP TS 24.229 [7].

4.3 URI and address assignments

In order to support SC to a subscriber, the following URI and address assignments are assumed:

a) in this version of the document, the SC UE for inter-UE transfer will be configured with an Inter UE Transfer SCC AS URI. The Inter UE Transfer SCC AS URI is used in the inter UE transfer procedures.