5.1 Introduction

29.5623GPP5G SystemHome Subscriber Server (HSS) servicesRelease 18Stage 3TS

The SBI capable HSS offers the following services via the Nhss_ims interface:

– Nhss_imsUEContextManagement Service

– Nhss_imsSubscriberDataManagement Service

– Nhss_imsUEAuthentication Service

– Nhss_gbaSubscriberDataManagement Service

– Nhss_gbaUEAuthentication Service

Table 5.1-1 summarizes the corresponding APIs defined for this specification.

Table 5.1-1: API Descriptions

Service Name	Clause	Description	OpenAPI Specification File	apiName	Annex
Nhss_imsUEContextManagement	6.1	Nhss UE Context Management Service for IMS	TS29562_Nhss_imsUECM.yaml	nhss-ims-uecm	A.2
Nhss_imsSubscriberDataManagement	6.2	Nhss Subscriber Data Management Service for IMS	TS29562_Nhss_imsSDM.yaml	nhss-ims-sdm	A.3
Nhss_imsUEAuthentication	6.3	Nhss UE Authentication Service for IMS	TS29562_Nhss_imsUEAU.yaml	nhss-ims-ueau	A.4
Nhss_gbaSubscriberDataManagement	6.4	Nhss Subscriber Data Management Service for GBA	TS29562_Nhss_gbaSDM.yaml	nhss-gba-sdm	A.5
Nhss_gbaUEAuthentication	6.5	Nhss UE Authentication Service for GBA	TS29562_Nhss_gbaUEAU.yaml	nhss-gba-ueau	A.6

All scenarios shown in the following clauses assume that the SBI capable HSS is stateful and stores information in local memory. However, the SBI capable HSS may be stateless and store information externally in the UDR. If so, the stateless SBI capable HSS may use Ud interface as specified in 3GPP TS 29.335 [7] to retrieve required data from the UDR and store them locally before processing an incoming request. Processing the incoming request may then include updating data in the UDR. After processing the incoming request, the SBI capable HSS may delete the locally stored data. When data stored in UDR is then shared among the different SBI capable HSS instances of the same group, as identified by HSS Group ID (see 3GPP TS 23.501 [2], clause 6.2.6), bulk subscriptions, as described in clause 4.15.3.2.4 of 3GPP TS 23.502 [3], are not applicable, i.e. an NF consumer (e.g. IMS-AS) only subscribes towards one of the SBI capable HSS instances within the group.

Editor’s Note: It is FFS if an informative Annex needs to be included to show how an IMS-AS/I-CSCF/S-CSCF can interact with a group of stateless SBI capable HSS instances.