3GPP Work Item description

This page contains informal descriptive text only.  See master WID page for further details.

Feature: Identification of Communication Services in IMS

3GPP has adopted the approach of creating a number of IMS enablers that can be used by a number of services.   The success of this has been demonstrated through the adoption of the IMS by other standardisation bodies (e.g. TISPAN, OMA, ….), some of which have finalised a service definition utilising the IMS.  A consequence of this approach is that neither the enabler being used, nor the requested media being used is sufficient to identify the particular communication service requested.

A means is required in order to identify the communication service requested for the following reasons:

- The network is required to identify the correct application server(s) to link into the SIP call path, if required.

- The media authorization policy may use a communication service identifier as input.

- It is desirable for the network to be able to authorize the use of a communication service

- Charging may use a communication service identifier as input.

- In a multi-UE scenario where a recipient has several UEs with different UE capabilities, it is useful to be able to route the SIP request to the UE(s) supporting a requested communication service.

- In order to enable the User Equipment to identify the correct application logic, while allowing for many services to be offered using the same enablers and media types.

- Often interworking requires knowledge of the services being interworked, as such interworking between an IMS based service and a non-IMS based service may benefit from the

  identification of the requested communication service.

- Allowing the network to authorise the use of the service for a particular user

- Communication service prioritisation in the case of network overload.

- To be an input into inter-operator interconnect service level agreements.

- Provide a scope for the IOP specifications related to a particular communication service

In addition to the above reasons, a communication service identifier also has the advantage or reducing the required co-ordination between standardisation bodies if the format and the encoding across these bodies was agreed and was the same.

The architectural and  requirements technical procedures for a communication service identifier and the administrative procedures related to a communication service identifier require study.

As a note, OMA has employed the feature tag as communication service identifier.

Note:  The introduction of a communication service identifier does not replace the public service identity (PSI), but indicates the particular communication service used.

The objective of this work item is to identify the architectural requirements and technical procedures as well as the administrative procedures for a communication service identifier.  This includes at least the following aspects:

- A frame work description for the usage and applicability of  the communication service identifier and its relationship with the PSI and other existing IMS mechanisms.

- Identifying the architectural requirements for a communication service identifier that enable the usage scenarios identified in the above justification section.

- Identifying requirements on compatibility and evolution of a communication service in relation to the communication service identifier. Describe the expected behaviour when the service

  identifier in the requesting SIP method doesn’t match with any of the service identifiers included in the registration process from the called UEs

- Identify the methods for administrative procedures for a communication service identifier, including the requirements upon when a service identifier value is required to be allocated.
 

In addition alternative mechanisms to identify communication services can be studied within the TR.

It is assumed that a Building Block Work Item will exist for the stage-3 specification work.