6a.4.4a Controller UE initiated modify media (media flow on the Controllee UE)

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

6a.4.4a.1 Controller UE and Controllee UE belong to the same IMS subscription

The information flow shows a Controller UE modifying a Media Flow that is originated from or terminated at the Controllee UE belonging to the same IMS subscription. As a pre-requisite, there exists a Collaborative Session with two media flows, Media Flow–A on the Controller UE (UE‑1) and Media Flow–B on the Controllee UE (UE‑2). Controller UE‑1 can initiate re-negotiation of media information of Controllee UE‑2 with remote party.

Figure 6a.4.4a.1-1: Controller UE initiated media modify on a Controllee UE belonging to the same IMS subscription

1. UE-1 sends a Modify Media Request to modify Media Flow-B on UE-2. The request includes media modification information pertaining to Media Flow-B. The IUT media modification request shall include enough information for the SCC AS to:

– identify that the modified media is Media Flow-B;

– identify that the modified media is on UE-2;

– identify the modification requested to Media Flow-B;

– keep the control of Collaborative Session in UE-1.

2. The SCC identifies Media Flow-B as associated with UE-2 and sends the Modify Media Request to UE-2. The request identifies the Media Flow–B that needs to be modified.UE-2 modifies the Media Flow–B. The SCC AS updates the Remote Leg with Media Flow–B modified.

3. The SCC AS sends Modify Media Response to UE-1.

6a.4.4a.2 Controller UE and Controllee UE belong to different IMS subscriptions under the same operator

The information flow shows a Controller UE modifying a Media Flow that is originated from or terminated at the Controllee UE belonging to different subscription. It is assumed that UE-1 and UE-2 belong to User-1 and User-2, respectively. As a pre-requisite, there exists a Collaborative Session with two media flows, Media Flow–A on the Controller UE (UE-1) and Media Flow–B on the Controllee UE (UE-2). Controller UE-1 can initiate re-negotiation of media information of Controllee UE-2 with remote party.

Figure 6a.4.4a.2-1: Controller UE initiated media modify on a Controllee UE belonging to different IMS subscription

1. UE-1 sends a Modify Media Request to SCC AS-1 serving UE-1 to modify Media Flow-B on UE-2. The request includes media modification information pertaining to Media Flow-B. The IUT media modification request shall include enough information for the SCC AS-1 to:

– identify that the modified media is Media Flow-B;

– identify that the modified media is on UE-2;

– identify the modification requested to Media Flow-B;

– keep the control of Collaborative Session in UE-1.

2. The SCC AS-1 authorizes the request from UE-1 as specified in clause 6a.12.

3. The SCC AS-1 sends the Modify Media Request to SCC AS-2 that serves UE-2 via S-CSCF-1 and S-CSCF-2.

4. If UE-2 is an IUT subscriber, the request is routed via SCC AS-2 which authorizes the request. The Modify Media Request is then routed on towards UE-2. If UE-2 is not an IUT subscriber, S-CSCF-2 routes the request according to normal procedures.

5. S-CSCF-2 forwards the Modify Media Request to UE-2. UE-2 modifies Media Flow-B.

6. The UE-2 sends a Modify Media Response towards SCC AS-1.

7 – 8. S-CSCF-2 routes the Modify Media Response back towards SCC AS-1 – via SCC AS-2 if UE-2 is an IUT subscriber.

9. The SCC AS-1 updates the Remote Leg with Media Flow–B modified upon receiving the Modify Media Response from UE-2.

10. The SCC AS-1 sends Modify Media Response to UE-1.