G.9 Immediate Codec Type Optimization

28.0623GPPInband Tandem Free Operation (TFO) of speech codecsService descriptionStage 3TS

The following protocol flow shows an example for Immediate Codec Type Optimation. Both sides start with AMR-NB, but indicate that AMR-WB is also supported. In this case no immediate TFO Setup in AMR-NB is performed because both sides can use better Codec Types and Configurations. No additional optimisation phase is necessary after AMR-WB TFO Setup.

Figure G.9-1: Immediate Codec Type Optimisation for AMR-WB with AMR-NB at call setup

Note: The TFO protocol is kept in the Contact state on both sides as long as contact to the distant side exists and the configurations (local and distant) indicate that TFO setup is possible with a preferred configuration (in this case AMR-WB). The numbers indicate the event number as listed in Table 10.4-1.

Annex H (normative):
Definition of the Generic Configuration Frames for TFO