3.2.3.1.10 Callback State

Callback State: A server conversation can only have a single outstanding conversation callback in progress at a time. Callback State is a boolean value that indicates if a conversation callback is in progress. See section 3.2.3.5.4.2 for more information on when a conversation callback is needed.

Callback State is set to true when a conversation callback is started and reset to false when it is completed.