If the hero listens to his answering machine and one important message is unexpected then he usually has two very short messages on the tape before, one spoken by a man, one by a women. "Here'a John! I see you tomorrow at eight.".... beep ... "This is Sallieeeeee! I'll call again later." ... beep .... and then finally "Ahhhh! The killer is .....". If however the message is expected be sure that it will be the first one on the tape.