AT&T MERLIN LEGEND System Reference Manual page 275

Features
Single-Line Telephones
2-226 Messaging
To return the call, the user presses a programmed Return Call button or presses
the Feature button and dials 27. To delete the message, the user presses a
programmed Delete Message button or presses the Feature button and dials
26. The Message LED goes off.
Multiline telephone users without a display cannot use programmed message
buttons or feature codes to respond to messages. Normally, the Message LED
is turned off by the system operator. However, an analog multiline telephone
user (excluding BE-34 telephones) can turn off the Message LED by pressing
the associated button. An analog multiline telephone user with a BIS-34
telephone and MLX telephone users without a display can turn off the LED by
pressing the Feature button and dialing 54.
The user should check with all message sources (system operator, fax, voice
messaging) before turning off the LED.
Posted Messages
To post a message, the user with an analog multiline telephone or an MLX
telephone without a display presses the programmed Posted Message button
(the green LED next to the programmed button flashes) and dials the code (01-
20) (the green LED next to the button is steady) for the message the user wants
posted. To cancel a posted message, the user presses the programmed Posted
Message button and dials 00 (the green LED next to the programmed button
goes off). An MLX display telephone user (including a QCC system operator)
uses the feature by pressing the Feature button and selecting the feature and
the message to post from the display.
Leave Message
To use the Leave Message feature while listening to ringback or the busy tone,
the single-line telephone user dials #25.
To use the Leave Message feature without calling the extension, the single-line
telephone user lifts the handset and dials #53 and the message receiver's
extension number.
In either case, if the receiver's message box is full or the message has a single-
line telephone or a multiline telephone without a display, the user hears a beep
indicating that the message was not left.
To cancel a message sent, the single-line user lifts the handset (while listening
to internal dial tone) and dials #*53 and the extension number where the
message was left.