K.2 GPRS (Iu mode only) aspects when connected to the IM CN subsystem

24.1733GPPIMS Multimedia telephony communication service and supplementary servicesRelease 18Stage 3TS

K.2.1 Procedures at the UE

K.2.1.1 General

The UE may support any of the procedures of clause K.2.1.

K.2.1.2 Application specific Congestion control for Data Communication (ACDC) procedure

The following information is provided to the non-access stratum:

– MO-MMTEL-voice-started;

– MO-MMTEL-voice-ended.

– MO-MMTEL-video-started; and

– MO-MMTEL-video-ended;

Upon request from a user to establish an originating multimedia telephony communication session as described in clause 5.2:

1) if only audio or only real-time text or only both audio and real-time text (see clause 4.2 for 3GPP systems) are offered in the multimedia telephony communication session, and no other originating multimedia telephony communication session initiated with offering only audio or only real-time text or only both audio and real-time textexists, the UE sends the MO-MMTEL-voice-started indication to the non-access stratum and continue with session establishment as described in clause 5.2;

2) if video is offered in the multimedia telephony communication session, and no other originating multimedia telephony communication session initiated with offering video exists, the UE sends the MO-MMTEL-video-started indication to the non-access stratum and continue with session establishment as described in clause 5.2.

When an originating multimedia telephony communication session ends (i.e. a response to a BYE or a failure response to the initial INVITE request is transferred), the originating multimedia telephony communication session was initiated with offering only audio or only real-time text or only both audio and real-time text (i.e. in the SDP offer in the initial INVITE request), and no other originating multimedia telephony communication session initiated with offering only audio or only real-time text or only both audio and real-time text exists, the UE sends the MO-MMTEL-voice-ended to the non-access stratum.

When an originating multimedia telephony communication session ends (i.e. a response to a BYE or a failure response to the initial INVITE request is transferred), the originating multimedia telephony communication session was initiated with offering video (i.e. in the SDP offer in the initial INVITE request), and no other originating multimedia telephony communication session initiated with offering video exists, the UE sends the MO-MMTEL-video-ended indication to the non-access stratum.

NOTE 1: If the UE supports other 3GPP specific mechanisms for communicating with the non-access stratum protocol implementation, e.g. DHCP discovery via PCO, then the UE is expected to support the transfer of information elements needed for the application specific congestion control for data communication enforcement.

NOTE 2: Adding or removing media during the multimedia telephony communication session has no impact on the information relating to application specific congestion control for data communication.