4 Overview of service level interworking for messaging services

29.3113GPPRelease 17Service Level Interworking (SLI) for messaging servicesTS

4.1 Introduction

The service level interworking for messaging services provides the interworking function between Instant Message or Chat Sessions and the Short Message to enable the communication between SM UE and Instant Message or CPM UE. The architecture for service level interworking is specified in 3GPP TS 23.204 [6].

4.2 Service level interworking between SM and IM

In order to provide the service level interworking between SM and IM, the following protocol mapping functionalities defined in 3GPP TS 23.204 [6] shall be supported:

– Instant Message mapped to Short Message over CS/PS;

– Instant Message mapped to Short Message over IP; and

– Short Message mapped to Instant Message.

4.3 Interaction with transport layer interworking

Both transport layer interworking and service level interworking shall be provided by IP-SM-GW. The interaction between transport layer interworking and service level interworking depends on the user subscription and authorization, on the UE capabilities, and on operator policy.

If a user only subscribes to either transport layer interworking or to service level interworking, only procedures defined for the subscribed interworking shall be performed by the IP-SM-GW.

If a user subscribes to both transport layer interworking and service level interworking, but the user is only authorised for one of the interworking when the message is processed, only the authorised interworking shall be performed by the IP-SM-GW.

If a user subscribes to both transport layer interworking and service level interworking, and is authorised for both, the behaviour of the IP-SM-GW depends on the specific scenario, on the registered capabilities of the UE, and finally is defined by operator policy and user preferences.

4.4 Service level interworking between SM and Chat Session

In order to provide the service level interworking between SM and Chat Session, the following protocol mapping functionalities defined in 3GPP TS 23.204 [6] shall be supported:

– Chat Session invitation request mapped to Short Message;

– Short Message mapped to Chat Session MSRP SEND request;

– Chat Session MSRP SEND request mapped to Short Message;

– Short Message mapped to Chat Session teardown request;

– Chat Session teardown request mapped to Short Message; and

– Event package for conference state information specified in IETF RFC 4575 [18] mapped to Short Message.