AT&T MERLIN LEGEND System Reference Manual page 271

Features
See Chapter 3, "System Applications,"
for detailed information on voice
messaging systems.
Receiving Messages
2-222 Messaging
The Leave Message feature can also be used to send a message to a co-worker
without a display only when the system includes a voice messaging system.
When Leave Message is used, the voice messaging system creates a pre-
programmed message and turns on the co-worker's Message LED to indicate
that a voice message was left.
If the message sender leaves another message for the same person before the
message receiver responds to a previous message, the previous message is
overwritten. A receiver with a display telephone sees only the sender's name (if
labels are programmed) and/or extension and date and time for the new
message. If the message is sent by using the voice messaging system, the
message receiver only receives the most recent message.
When the system does not include a voice messaging system and a user with
any telephone tries to use the Leave Message feature to send a message to a
person with a single-line telephone or a multiline telephone without a display, the
sender hears a single beep indicating that a message must be left with the
system operator. If the message sender has a display telephone, the message
"Cannot Send Message" is displayed.
When a user tries to send a message by using the Leave Message feature for a
co-worker with a display telephone whose message box is full, the receiver's
telephone continues to ring and the sender's telephone beeps once. If the
sender has a display telephone, "Message Box Full" is displayed, and the
sender must leave a message with the system operator instead.
Users can cancel a sent message by pressing the Feature button and dialing
*53 plus the extension where they left the message.
When the Message LED on a user's telephone is on or when a single-line
telephone user hears the recall dial tone when lifting the handset, there is a
message waiting for that person or for the calling group (if the telephone is
programmed as a Message Waiting Receiver for a calling group). The message
can be from the following sources:
The system operator
The voice messaging system, if connected
A fax machine if the telephone is programmed as a Message Waiting
Receiver for a fax
Another user if the message receivers telephone has a display
From one to four telephones can be designated to receive message-waiting
indications when a fax transmission is received on a specific fax machine. The
Message LED is turned on when the fax message threshold is exceeded. The
fax message threshold is the length of time (0-30 seconds) before the system
assumes a fax has arrived.
Note: Fax machines can only send message-waiting indication. They cannot
receive message-waiting indication from other fax machines.