5 Functional entities

24.2923GPPIP Multimedia (IM) Core Network (CN) subsystem Centralized Services (ICS)Release 17Stage 3TS

5.1 Introduction

This clause associates the functional entities described for the IM CN subsystem and for the CS domain, with the ICS roles described in the stage 2 architecture document (see 3GPP TS 23.292 [6]).

5.2 User Equipment (UE)

A UE establishing the service control signalling path over Gm, that is compliant with this specification shall implement the role of ICS UE capabilities defined in:

– subclause 6.2;

– subclause 7.2 apart from subclause 7.2.4;

– subclause 8.2;

– subclause 9.2;

– subclause 10.2 apart from subclause 10.2.5; and

– subclause 11.2 apart from subclause 11.2.4.

A UE that is compliant with this specification may support establishing the service control signalling path over I1. A UE that supports establishing the service control signalling path over I1 shall implement the role of ICS UE capabilities defined in:

– subclause 7.2.4;

– subclause 10.2.5; and

– subclause 11.2.4.

5.3 MSC Server enhanced for ICS

Where the MSC server is supporting I2, the MSC server is enhanced for ICS. The MSC Server enhanced for ICS shall provide the UA role as defined in Annex A of 3GPP TS 24.229 [11], with the exceptions and additional capabilities as described in subclauses 6.3, 7.3, 8.3, 9.3, 10.3 and 11.3.

5.4 Application Server (AS)

The SCC AS provides the following roles:

a) ICS User Agent (IUA) as defined in 3GPP TS 23.292 [6] subclause 5.3.1;

b) Terminating Access Domain Selection (T-ADS) as defined in 3GPP TS 23.292 [6] subclause 5.3.1; and

c) an AS performing 3rd party call control acting as a routeing B2BUA as defined in 3GPP TS 24.229 [11] subclause 5.7.5.1.

An AS implementing the ICS application shall implement one or more of the roles IUA or T-ADS. Both roles can be co-located.

3GPP TS 24.294 [11B] defines mechanisms for the support of establishing the service control signalling path over I1. Support of such a mechanism is optional for the SCC AS.