You can connect an incoming call directly to an announcement and then disconnect the call after the announcement has completed in one of two ways:
Administer an announcement extension as the incoming destination. The caller is directed to the announcement and is disconnected, without being queued for a split.
Administer an announcement extension as a point in a split coverage path. Calls that have been in the queue for a long time are forced to go directly to the announcement and are disconnected.