6a.4.5 Controllee UE initiated release media on itself

23.2373GPPIP Multimedia Subsystem (IMS) Service ContinuityRelease 17Stage 2TS

As per standard IMS UE behaviour, a Controllee UE may initiate a release of a media flow that it terminates. In this case, this media release on the access leg is notified to the Controller UE, which may decide to transfer this media flow to another UE under the same subscription, or to remove it from the Collaborative Session (i.e. remove it on the remote leg).

The following information flow shows a Controllee UE initiating the release of a media flow that it terminates, and Controller UE being informed of this release by the SCC AS. As a pre-requisite, there exists a Collaborative Session of which UE-1 is the Controller UE and UE-2 is a Controllee UE terminating a media flow, Media Flow A. There may be other media flows (on UE 1, UE-2 or other UEs) within the Collaborative Session; such media flows and UEs are not shown on this information flow; they shall not be impacted by this operation.

Figure 6a.4.5-1: Controllee UE initiated release media flow on itself

1. Controllee UE-2 sends a request to release Media Flow A (that it terminates), using standard IMS procedure.

2. The SCC AS identifies that Media Flow A is under Collaborative Session control of UE-1. The SCC AS indicates to Controller UE-1 that Controllee UE-2 has released Media Flow A.

3. Controller UE-1 initiates one of the following procedures, in order to transfer Media Flow A to another UE under the same subscription, or to remove it from the Collaborative Session:

– Controller UE initiated media transfer from Controllee UE to Controller UE, specified in clause 6a.3.2;

– Controller UE initiated media transfer from Controllee UE to another Controllee UE, specified in clause 6a.3.3;

– Controller UE initiated release media (media flow on the Controllee UE), specified in clause 6a.4.3;

– Controller UE initiated release Collaborative Session, specified in clause 6a.5.1.

4. The SCC AS updates the Remote Leg while executing the procedure initiated by Controller UE-1 at step 3.