IP Multimedia Subsystem (IMS) Service Continuity; Stage 2
The present document specifies the architectural requirements and procedures for delivery of IMS Service Continuity.
TS 23.206 [3] is migrated to this specification.
The scope of the specification includes:
- Access Transfer related functionality:
- PS-CS Access Transfer;
- PS-PS Access Transfer;
- PS-PS Access Transfer in conjunction with PS-CS Access Transfer;
- Adding and/or removing media flows to support service;
. MSC Server assisted mid-call feature;
- SRVCC session transfer of IMS emergency session;
- DRVCC session transfer of IMS emergency session.
- Inter‑UE Transfer related functionality:
- Establishment and release of a Collaborative Session;
- Addition of media flows to, modification of media flows in, and release of media flows from a Collaborative Session;
- Transfer of media flows from one UE to another;
- Transfer of the Collaborative Session Control with or without transfer of media flows;
- Transfer of all media flows to a target UE without establishing a Collaborative Session;
- Session discovery;
- Inter-UE Transfer initiated by the target UE or by the SCC AS;
- Replication of media flows by means of Inter-UE Transfer procedures;
- Authorization and other aspects to support Inter-UE Transfer across multiple IMS subscriptions.
The solution is restricted to service continuity using IMS procedures, i.e. mobility mechanisms on the IP-CAN level are not within the scope of this specification.