This object specifies the backward signal indicating that a recorded announcement will follow, giving the gateway advance notice to switch into announcement-playback handling for the call. This signal is what tells the gateway not to expect a normal answer/ringback sequence next but instead a network-played message, which affects how call-progress state machines and call detail record logic should classify the call outcome. Before playing a message like 'the number you have dialed has changed', the terminating exchange would send this signal so the originating gateway's call-progress logic correctly logs the call as an announcement rather than a completed conversation.