scope:

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.

- 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.