7 Functional requirements of HSS

23.2183GPPIM call modelIP Multimedia (IM) session handlingRelease 17Stage 2TS

7.1 Subscriber data related storage requirements for HSS

HSS stores information required by:

– S-CSCFs (downloaded via Cx interface). Data model and abstract syntax notation are described in 3GPP TS 29.228 [8];

– IM-SSF Application Servers (downloaded via Si or Sh interface);

– Application Servers (downloaded via Sh interface).

The service related data shall be transparent to HSS, this requires the HSS has some means to differentiate the source of the request for the data, therefore, the HSS can respond with the data the request asks for.

7.2 Interfaces defined for HSS

7.2.1 HSS – CSCF (Cx) interface

This interface is used to send subscriber data to the S-CSCF, including Filter Criteria (and their priority); which indicates which SIP requests should be proxied to which Application Servers.

The protocol used between the HSS and CSCF (Cx Interface) is specified in 3GPP TS 29.228 [8] and 3GPP TS 29.229 [17].

7.2.2 HSS – Application Server (Sh) interface

The Sh interface is between the HSS and the SIP Application Servers and the OSA SCS and may be used for transferring User Profile information such as user service related information or user location information or charging function addresses. Requirements for the Sh interface are specified in 3GPP TS 23.228 [3].

The Sh interface also supports mechanisms that allow Application Servers to activate/deactivate their own existing initial filter criteria stored in the HSS on a per subscriber basis.

The protocol used between the HSS and AS (Sh Interface) is specified in 3GPP TS 29.328 [18] and 3GPP TS 29.329 [19].

7.2.3 HSS – CSE interface

The protocol used on the interface between the HSS and the CAMEL Service Environment (CSE) is the MAP protocol [16].

7.2.4 HSS – IM-SSF Application Server interface

The interfaces between the HSS and the IM-SSF Application Server are:

– the Si interface when the MAP protocol as specified in 3GPP TS 23.278 [9] and 3GPP TS 29.002 [16] is used

– the Sh interface when the Diameter based protocol as specified in 3GPP TS 29.328 [18], 3GPP TS 29.329 [19] and 3GPP TS 29 364 [26] is used

The Si and the Sh interfaces between HSS and the IM-SSF Application Server are used for transferring IMS CAMEL specific information.

7.3 Procedures during IP multimedia registration

These procedures are described in 3GPP TS 29.228 [8].

7.4 Procedures during IP multimedia sessions

These procedures are described in 3GPP TS 29.228 [8].