Source : Free On-Line Dictionary of Computing

voice mail
     
         Any system for sending, storing and
        retrieving {audio} messages, like a telephone answering
        machine.
     
        A voice mailbox is typically associated with a telephone
        number or extension.  When the number is called and the line
        is busy or not answered, the caller hears a message left by
        the owner and is given instructions for leaving a message or
        other available options, such as paging the individual or
        being transferred to an operator.  The owner of a mailbox can
        change the outgoing message or listen to incoming messages
        after entering a {PIN}.  Members of a voice mail system can
        generally forward or {broadcast} messages to other members'
        boxes.
     
        The experience of two people trying to reach other by
        telephone but always reaching each other's voice mail is
        referred to as "(tele)phone tag".
     
        (1996-11-03)