3 Definitions and abbreviations

23.2923GPPIP Multimedia Subsystem (IMS) centralized servicesRelease 17Stage 2TS

3.1 Definitions

For the purposes of the present document, the terms and definitions given in TR 21.905 [1] 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 [1].

Access Leg: The call leg between the UE and the SCC AS.

Correlation MSISDN: An MSISDN used for correlation of sessions.

CS Bearer Control Signalling Path: Signalling path used to control the call established to set up the CS media bearer between the UE and IMS.

CS domain Routing Number (CSRN): A CS Domain Routing Number (CSRN) is a routable number that is used to route a call from the IM CN subsystem to the UE in the CS domain. See TS 23.003 [5] for more information.

ICS UE: An IMS capable UE with additional ICS-specific functionality.

ICS User: An ICS user is an IMS subscriber that receives communication services centralized in IMS, regardless of the attached access type (e.g. CS domain access, or IP-CAN).

IMS Centralized Services: See definition in TS 22.101 [9].

IP Multimedia Routing Number (IMRN): See definition in TS 23.237 [12].

MSC Server enhanced for ICS: An MSC Server that supports the network based ICS functionality.

Remote Leg: The call leg formed between the SCC AS and the remote end for presentation of the SIP UA behaviour to IMS on behalf of the UE. The TAS, and other Application Servers are invoked on the Remote Leg.

Service Control Signalling Path: Signalling path established between the UE and the SCC AS, either directly via an IP-CAN or via CS network elements for service control signalling.

3.2 Abbreviations

For the purposes of the present document, the abbreviations given in TR 21.905 [1] 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 [1].

5GC 5G Core Network

ADS Access Domain Selection

CAA CS Access Adaptation

CGI Cell Global Identifier

C-MSISDN Correlation MSISDN

CSRN CS domain Routing Number.

DN Directory Number (e.g. MSISDN)

ICS IMS Centralized Services

IMRN IP Multimedia Routing Number.

IN Intelligent Network

IUA ICS User Agent

MMTel Multimedia Telephony

SAI Service Area Identification

SCC AS Service Centralization and Continuity Application Server

T-ADS Terminating ADS

TAS Telephony Application Server

UDM Unified Data Management

UE T-ADS UE assisted Terminating ADS