This TS provides the ETSI TISPAN endorsement of TS 23.206
"Voice Call Continuity (VCC) between Circuit Switched (CS) and IP Multimedia Subsystem (IMS); Stage 2: Release 7".
The current VCC solution explained in the TS 23.206
is essentially defined for a core IMS provider that is a mobile operator (that has also CS domain). In Informative Annex ZA theres is a possible scenario how the solution can be extended to a generic IMS operator (e.g. when fixed network operator and CS mobile network operator are separate organisations).