An application server includes an asynchronous event manager configured for selectively terminating an instance executing a messaging session, based on detecting a message from a gateway server that the incoming call is a call having a type that differs from the prescribed type intended for the messaging session. The asynchronous event manager terminates the instance by setting global variables accessible by the instance that specify that the call is rejected (i.e., the connection between the gateway and the instance executing the messaging session is terminated) due to the incoming call being of a different type than intended for that messaging session, for example the call being a fax call instead of a voice call. The instance executing the messaging session checks the global variables prior to committing to execution of critical operations that affect stored subscriber messaging data, for example before sending a recorded message for storage, or changing a state of a stored message from a new message to a stored message or deleted message. If the global variables indicate that the messaging session should be terminated, the instance rolls back the necessary data structures by deleting any necessary data (e.g., log entries, application state information, recorded messages, etc.), and terminates the instance.