AA.1 General

23.2283GPPIP Multimedia Subsystem (IMS)Release 18Stage 2TS

AA.1.0 Overview

This Annex AA describes support for SBA for IMS nodes. This Annex is intended to be used in conjunction with 5GC.

AA.1.1 Architectural Support

Figure AA.1.1-1 shows the architecture to support SBA interactions between IMS entities.

Figure AA.1.1-1: System Architecture to support SBA in IMS

Figure AA.1.1-2 shows the architecture using the reference point representation.

Figure AA.1.1-2: System Architecture to support SBA in IMS in reference point representation

AA.1.2 Reference point to support SBA in IMS

Following reference points are realized by service-based interfaces in IMS:

N5: Reference point between the PCF and an AF.

NOTE: P-CSCF acts as an AF from PCF point of view. N5 Reference point is defined in TS 23.501 [93].

N70: Reference point between an SBI capable I/S-CSCF and an SBI capable HSS.

N71: Reference point between an SBI capable IMS AS and an SBI capable HSS.

AA.1.3 Service based interface to support SBA in IMS

Npcf: Service-based interface exhibited by PCF.

Nhss: Service-based interface exhibited by an SBI capable HSS.

These SBI services provide equivalent functionality to the Diameter Rx and Cx/Sh reference points.

To support co-existence of IMS nodes supporting SBA services and IMS nodes not supporting SBA services SBI enabled IMS nodes may support both SBI and non-SBI interfaces.