184.108.40.206.1.4 Processing a Training PDU
The structure and fields of the Training PDU are specified in section 220.127.116.11.
The Training PDU MAY be sent by the server at any time and during any sequence, not just during the initialization sequence. The only prerequisite is that version exchange MUST have occurred.
If the client advertises a UDP port during version exchange, the Training PDU MAY<13> be sent over UDP or over virtual channels. Any subsequent audio data SHOULD be sent over the same transport method that is used to send the Training PDU by the server.
The client MUST respond with a Training Confirm PDU using the same transport on which the Training PDU was received.