For the purposes of the present document, the terms and definitions given in TR 21.905
and the following apply. A term defined in the present document takes precedence over the definition of the same term, if any, in TR 21.905
Anchoring in IMS:
Insertion of the Domain Transfer Function in the signalling path of the voice call/session establishment in order to enable the capability of domain transfer for this call/session.
IP Multimedia Routing Number (IMRN):
An IMRN is a routable number that points to the IM CN subsystem. In a roaming scenario, the IMRN has the same structure as an international ISDN number. The Tel URI format of the IMRN is treated as a PSI within the IM CN subsystem.
CS Domain Routing Number (CSRN):
A CSRN is a number that is used to route a call from the IM CN subsystem to the user in the CS domain.
Transfer of the access leg of a voice call on a UE from CS domain to IMS and vice versa while maintaining active session.
This is the call control leg between the VCC UE and the DTF.
This is the call control leg between the DTF and the remote party from the VCC subscriber's perspective.
VCC Domain Transfer Number (VDN):
User Equipment supporting the VCC feature. The VCC UE is defined in clause 5.3.2
of this document.
A public telecommunication number, as defined by ITU-T Recommendation E.164  used by the UE to request the DTF to perform Domain Transfer to the CS domain from the IMS.
VCC Domain Transfer URI (VDI):
A SIP URI used by the UE to request the DTF to perform Domain Transfer to the IMS from the CS domain.
For the purposes of the present document, the abbreviations given in TR 21.905
and the following apply. An abbreviation defined in the present document takes precedence over the definition of the same abbreviation, if any, in TR 21.905
Third party call control
CS Adaptation Function
CS Domain Routing Number
Domain Selection Function
Domain Transfer Function
Initial Filter Criteria
IP Multimedia Routing Number
Public Service Identity
Voice Call Continuity
VCC Domain Transfer URI
VCC Domain Transfer Number