7.9 Addition/Removal of video media flow
23.2923GPPIP Multimedia Subsystem (IMS) centralized servicesRelease 17Stage 2TS
7.9.1 Addition/Removal of video media flow for Non ICS UE
7.9.1.1 Overview
The procedures in this clause and the following clauses are applicable only to 3GPP systems.
For IMS sessions that use CS media established by the non ICS UE, the MSC Server enhanced for ICS shall perform the necessary interworking between the I2 reference point and CS SCUDIF signalling described in TS 23.172 [37] and TS 24.008 [6] to add/remove the video media flow through SCUDIF if supported by the CS access network.
In the case that the non ICS UE is attached to the MSC Server not enhanced for ICS, the MGCF shall perform the service change procedures to add/remove the video media flow as specified in TS 29.163 [11].
The non ICS UE can also use the redial mechanism as defined in TR 23.903 [39] for switching between voice and video services.
7.9.1.2 Addition/Removal of video media flow through SCUDIF using I2 reference point
Figure 7.9.1.2-1 describes how a video media flow is added to an ongoing speech session for the non ICS UE via the MSC Server enhanced for ICS. Change from multimedia (i.e. speech and video) to speech can be achieved in a similar way.
Figure 7.9.1.2-1: Addition of video media flow for non ICS UE via the MSC Server enhanced for ICS
1. The non ICS UE A sends a MODIFY message requesting service change from speech to multimedia (i.e. video and voice) as specified in TS 23.172 [37].
2. The MSC Server initiates interaction with the MGW instructing it to modify bearer characteristics.
3. The MSC Server sends a re-INVITE message that offers the adding of the video media to the ongoing speech session to the S‑CSCF.
4. The S‑CSCF sends the re-INVITE to the SCC AS which has been inserted at session establishment.
5. The SCC AS sends the re-INVITE to the S‑CSCF.
6. The S‑CSCF forwards the re-INVITE to UE B.
7. Completion of the session and bearer setup procedures, where upon the establishment of the multimedia connection, the MSC Server shall perform the video codec negotiation and set up the multimedia bearer based on the procedures defined in TS 29.163 [11].
7.9.1.3 Addition/Removal of video media flow through SCUDIF via the MSC Server not enhanced for ICS
Figure 7.9.1.3-1 describes how a video media flow is added to an ongoing speech session for the non ICS UE via the MSC Server which is not enhanced for ICS. Change from multimedia (i.e. speech and video) to speech can be achieved in a similar way.
Figure 7.9.1.3-1: Addition of video media flow for non ICS UE via the MSC Server not enhanced for ICS
1. The non ICS UE A sends a MODIFY message requesting service change from speech to multimedia (i.e. video and voice) as specified in TS 23.172 [37].
2. The MSC Server sends the Modify Codec message to the MGCF indicating the change from speech to multimedia (i.e. video and voice).
3. The MGCF initiates interaction with the IMS-MGW instructing it to modify bearer characteristics.
4. The MGCF sends the re-INVITE that offers the adding of the video media to the ongoing speech session to the S‑CSCF.
5-7. Steps 5-7 in Figure 7.9.1.3-1 are identical to Steps 4-6 in Figure 7.9.1.2-1.
8. Completion of the session and bearer setup procedures, where upon the establishment of the multimedia connection, the MGCF/IMS-MGW shall perform the procedures as specified in TS 29.163 [11] to set up the multimedia bearer.
7.9.2 Addition/Removal of video media flow for ICS UE
7.9.2.1 Overview
The procedures in this clause and the following clauses are applicable only to 3GPP systems.
For the IMS sessions that use CS media established by the ICS UE, adding/removing of video media flow can be made by updating the CS access leg through SCUDIF procedures as specified in TS 23.172 [37], or by using redial mechanism over the CS access leg as defined in TR 23.903 [39] if SCUDIF is not supported.
7.9.2.2 Addition/Removal of video media flow through SCUDIF using Gm Reference Point
Figure 7.9.2.2-1 describes how a video media flow is added to an ongoing speech session through SCUDIF for the ICS UE over the Gm reference point. Change from multimedia (i.e. speech and video) to speech can be achieved in a similar way.
Figure 7.9.2.2-1: Addition of video media flow for ICS UE through SCUDIF using Gm reference point
1. The ICS UE A sends a re-INVITE message that offers the adding of the video media to the ongoing speech session to the S‑CSCF.
2. The S‑CSCF sends the re-INVITE message to the SCC AS.
3. The SCC AS sends a 200 OK message to the S‑CSCF.
4. The S‑CSCF forwards the 200 OK to the ICS UE A.
5. Completion of service change from speech to video call as specified in clause 7.9.1.2 if the ICS UE is attached to the MSC Server enhanced for ICS, or as specified in clause 7.9.1.3 if the ICS UE is attached to the MSC Server not enhanced for ICS.
7.9.2.3 Addition/Removal of video media flow through SCUDIF using I1 Reference Point
Figure 7.9.2.3-1 describes how a video media flow is added to an ongoing speech session through SCUDIF for the ICS UE over the I1 reference point. Change from multimedia (i.e. speech and video) to speech can be achieved in a similar way.
Figure 7.9.2.3-1: Addition of video media flow for ICS UE through SCUDIF using I1 reference point
1. The ICS UE A sends a Call MODIFY message to the SCC AS requesting service change from speech to multimedia (i.e. video and voice).
2. The SCC AS sends a Call MODIFY Response message to the ICS UE A.
3. Completion of service change from speech to video call as specified in clause 7.9.1.2 if the ICS UE is attached to the MSC Server enhanced for ICS, or as specified in clause 7.9.1.3 if the ICS UE is attached to the MSC Server not enhanced for ICS.
7.9.2.4 Addition/Removal of video media flow through redial using Gm Reference Point
Figure 7.9.2.4-1 describes how a video media flow is added to an ongoing speech session through redial for the ICS UE which is attached to the MSC Server enhanced for ICS over the Gm reference point. Change from multimedia (i.e. speech and video) to speech can be achieved in a similar way.
Figure 7.9.2.4-1: Addition of video media flow for ICS UE via the MSC Server enhanced for ICS through redial using Gm reference point
1. The ICS UE A sends a re-INVITE message that offers the adding of the video media to the ongoing speech session to the S‑CSCF.
2. The S‑CSCF sends the re-INVITE message to the SCC AS which has been inserted at session establishment.
3-4. The SCC AS sends 200 OK to the ICS UE A via the S‑CSCF.
5. The ICS UE A sends a CS call disconnect message to the MSC server to release the existing CS access leg.
6. The MSC server sends the BYE message to the S‑CSCF.
7. The S‑CSCF forwards the BYE message to the SCC AS.
8. Completion of the CS access leg release procedure.
9. The ICS UE A sends a CS call setup message to the MSC server to establish a new CS access leg supporting video and speech media.
10. The MSC server sends an INVITE message to the S‑CSCF.
11. The S‑CSCF sends the INVITE to the SCC AS.
12. The SCC AS sends a re-INVITE message to the S‑CSCF that offers the adding of the video media to the ongoing speech session to update the remote leg.
13. The S‑CSCF sends the re-INVITE to UE B.
14. Completion of the session and bearer setup procedures, where upon the establishment of the multimedia connection, the MSC Server shall perform the video codec negotiation and set up the multimedia bearer based on the procedures defined in TS 29.163 [11].
Figure 7.9.2.4-2 describes how a video media flow is added to an ongoing speech session through redial for the ICS UE which is attached to the MSC Server not enhanced for ICS over the Gm reference point. Change from multimedia (i.e. speech and video) to speech can be achieved in a similar way.
Figure 7.9.2.4-2: Addition of video media flow for ICS UE via the MSC Server not enhanced for ICS through redial using Gm reference point
1-5. Steps 1-5 in Figure 7.9.2.4-2 are identical to Steps 1-5 in Figure 7.9.2.4-1.
6. The MSC server sends a REL message to the MGCF.
7. The MGCF sends a BYE message to the S‑CSCF.
8-10. Steps 8-10 in Figure 7.9.2.4-2 are identical to Steps 7-9 in Figure 7.9.2.4-1.
11. The MSC server sends an IAM message to the MGCF.
12. The MGCF sends an INVITE message to the S‑CSCF.
13-15. Steps 13-15 in Figure 7.9.2.4-2 are identical to Steps 11-13 in Figure 7.9.2.4-1.
16. Completion of the session and bearer setup procedures, where upon the establishment of the multimedia connection, the MGCF/IMS-MGW shall perform the procedures as specified in TS 29.163 [11] to set up the multimedia bearer.
7.9.2.5 Addition/Removal of video media flow through redial using I1 Reference Point
Figure 7.9.2.5-1 describes how a video media flow is added to an ongoing speech session through redial for the ICS UE which is attached to the MSC Server enhanced for ICS over the I1 reference point. Change from multimedia (i.e. speech and video) to speech can be achieved in a similar way.
Figure 7.9.2.5-1: Addition of video media flow for ICS UE via the MSC Server enhanced for ICS through redial using I1 reference point
1. The ICS UE A sends a Call MODIFY message that offers the adding of the video media to the ongoing speech session to the SCC AS.
2. The SCC AS sends a Call MODIFY Response message to the ICS UE A.
3. The ICS UE A sends a CS call disconnect message to the MSC server to release the existing CS access leg.
4. The MSC server sends the BYE message to the S‑CSCF.
5. The S‑CSCF forwards the BYE message to the SCC AS.
6. Completion of the CS access leg release procedure.
7. The ICS UE A sends a CS call setup message to the MSC server to establish a new CS access leg supporting video and speech media.
8. The MSC server sends the INVITE to the S‑CSCF.
9. The S‑CSCF sends the INVITE to the SCC AS.
10. The SCC AS sends a re-INVITE to the S‑CSCF that offers the adding of the video media to the ongoing speech session to update the remote leg.
11. The S‑CSCF sends the re-INVITE to UE B.
12. Completion of the session and bearer setup procedures, where upon the establishment of the multimedia connection, the MSC Server shall perform the video codec negotiation and set up the multimedia bearer based on the procedures defined in TS 29.163 [11].
Figure 7.9.2.5-2 describes how a video media flow is added to an ongoing speech session through redial for the ICS UE which is attached to the MSC Server not enhanced for ICS over the I1 reference point. Change from multimedia (i.e. speech and video) to speech can be achieved in a similar way.
Figure 7.9.2.5-2: Addition of video media flow for ICS UE via the MSC Server not enhanced for ICS through redial using I1 reference point
1. The ICS UE A sends a Call MODIFY message that offers the adding of the video media to the ongoing speech session to the SCC AS.
2. The SCC AS sends a Call MODIFY Response message to the ICS UE A.
3. The ICS UE A sends a CS call disconnect message to the MSC Server to release the existing CS access leg.
4. The MSC Server sends a REL message to the MGCF.
5. The MGCF sends a BYE message to the S‑CSCF.
6-8. Steps 6-8 in Figure 7.9.2.5-2 are identical to Steps 5-7 in Figure 7.9.2.5-1.
9. The MSC Server sends an IAM message to the MGCF.
10. The MGCF sends the INVITE to the S‑CSCF.
11-13. Steps 11-13 in Figure 7.9.2.5-2 are identical to Steps 9-11 in Figure 7.9.2.5-1.
14. Completion of the session and bearer setup procedures, where upon the establishment of the multimedia connection, the MGCF/IMS-MGW shall perform the procedures as specified in TS 29.163 [11] to set up the multimedia bearer.