Called on session engine shutdown.
Typically the session engine will try to clean up before shutting down by signing off all interviewers. The session engine will only call the destructor without cleaning up first if there is an emergency. Therefore, if the destructor is called without cleaning up, the dialing provider should only clean up what can be cleaned up quickly and without event handling. As mentioned in
Fail over, it might be useful to support a recovery process that occurs during SignOn and supports returning records so they are not stuck in the ACTIVE queue.