For the purposes of the present document, the [following] terms and definitions [given in ... and the following] apply.
Bearer Control Signalling Path:
Standard CS signalling path used to control the call established to setup CS voice bearer between the UE and IMS.
CS Access Signalling:
Standard CS signalling used between the UE and the CS network.
ICS Enhanced MSC Server:
The ICS UE is a User Equipment that contains the new UE capabilities defined in this document and that is capable of receiving telephony services and other services offered by IMS while the voice bearer is established via CS. An ICS UE can also be a UE which can access IMS via an IP-CAN that supports the full duplex speech component of the IMS multimedia telephony service, and follows the procedure defined in TS 22.101
, TS 22.173
, TS 23.228
, TS 24.229
and TS 24.173
. An ICS UE is not necessarily capable of VCC.
An MSC Server which has been enhanced with ICS capability.
The non-ICS UE is a User Equipment that does not contain the new capabilities defined in this document. A non-ICS UE is not necessarily capable of VCC.
The call leg between the ICCF and the remote end. It is formed at the ICCF for presentation of the SIP UA behaviour to IMS on behalf of the UE. The TAS, VCC AS and other Application Servers are invoked on the RUA Leg.
Session Control Signalling Path:
Signalling path established between the UE and the ICCF, either directly via PS through an IP-CAN or via CS network elements such as the VMSC and the HSS for enablement of IMS control of user sessions at the ICCF when using CS voice bearers.
Session Transfer Identifier:
Session Transfer Identifier is an identifier used by Domain Transfer Function to identify the anchored sessions destined to or originated from a specific UE. It is used by the UE or the network to identify the specific anchored session to perform Domain Transfer.
The call leg between the ICCF and the UE. It is formed at the ICCF by combining of the CS call established between the UE and the ICCF to set up the voice bearer, with the control information communicated between the UE and ICCF to enable the completion of the call towards the remote end.
For the purposes of the present document, the following abbreviations apply:
CS Access Adaptation Function
IMS CS Control Channel
IMS CS Control Channel implemented over the CS domain
IMS CS Control Channel implemented over the PS domain
IMS Centralized Services
IMS CS Control Protocol
IMS CS Control Function
ICS Enhanced MSC Server
Local CS Access Adaptation Function
Local CS Access Adaptation Function-network equivalent
Remote User Agent
Remote CS Access Adaptation Function
Voice Call Continuity