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".