Single-cassette answering machines contain the outgoing message at the beginning of the tape and incoming messages on the remaining space. They first play the announcement, then fast-forward to the next available space for recording, then record the caller's message. If there are many previous messages, fast-forwarding through them can cause a significant delay. This delay is taken care of by playing back a beep to the caller, when the TAD is ready to record. This beep is often referred to in the greeting message, requesting that the caller leave a message "after the beep".