4.3.9 User interaction and in-band information

23.1723GPPRelease 17Stage 2Technical realization of Circuit Switched (CS) multimedia service UDI/RDI fallback and service modificationTS

The MSC provided announcements and tones do not work, if the negotiated BC is a multimedia BC. Most often the in-band information is connected to the originating UE but the same rules apply for the terminating UE. The following rules apply:

1) Before sending the CONNECT message the originating MSC may insert in-band information if CALL PROCEEDING message indicates speech as the selected or preferred service. When fallback to multimedia occurs after CALL PROCEEDING but before CONNECT, the MSC may insert in-band information.

2) Before sending the CONNECT message the originating MSC shall not insert in-band information, if CALL PROCEEDING message indicates multimedia as the selected or preferred service. When fallback to speech occurs after CALL PROCEEDING but before CONNECT, the MSC shall not insert in-band information.

3) After the CONNECT message to/from the UE the originating/terminating MSC may insert in-band information, if the selected service is speech. Otherwise, the MSC shall not insert any in-band information. As an option, if the call is to be cleared, the MSC may perform an in-call modification to speech prior to the insertion of the in-band information.

4) During the call setup phase the terminating MSC, transit MSC and GMSC may insert in-band information, if the selected/preferred service received from the originating switch is speech. Otherwise the terminating MSC, transit MSC and GMSC shall not insert any in-band information during the call setup phase.

5) In the active phase of the call the terminating MSC, transit MSC and GMSC may insert in-band information, if the selected service is speech. Otherwise the terminating MSC, transit MSC and GMSC shall not insert any in-band information. As an option, if the call is to be cleared, the terminating MSC, transit MSC or GMSC may perform an in-call modification to speech prior to insertion of the in-band information.