1.3.3 Format Change Sequence
The format change sequence provides a mechanism for the server to request that the client use a different format for encoding the audio data. The server initiates the sequence by sending a Format Change PDU, identifying the server's desired format out of the list that was agreed on during the initialization sequence. The client will then confirm this change of format by sending a Format Change PDU specifying the same format. From this point, the client will encode audio data using the new format.
Figure 3: Format change sequence