AT&T MERLIN LEGEND Reference page 52

Features
3. Dial the feature code assigned by the local telephone company to activate
Automatic Callback.
Wait for the confirmation tone (a three-burst tone) to ensure that the
feature was activated correctly.
The telephone number from which the last call was received on the BRI
line is automatically dialed by the central office.
If the telephone number being called is available, you hear ringback.
If the telephone number being called is busy, the central office "camps"
or queues the recall attempt at the called number. When the number
becomes available, the central office calls you back on the BRI line used
to place the call. All telephones sharing the Personal Line button ring with
a priority ring (four-burst ring for MLX telephones and three-burst ring for
analog telephones) to indicate the completed call.
Line Button Call Received Is Not Known
If more than one BRI line is assigned as a Personal Line button on the telephone
and you do not know which Personal Line button received the last BRI call, follow
these steps to activate the Automatic Callback feature:
1. While the handset is on-hook, press the programmed BRI Access button.
The green LED next to the BRI Access button flashes.
If the telephone is an MLX display telephone, the following prompt is
shown:
Dial 4 for In, 6 for Out
2, Dial a 4, which represents the letter "I" for incoming call.
The red LED moves to the last Personal Line button used to receive an
incoming call on a BRI line.
The green LED next to the BRI Access button goes off.
3. Lift the handset or, if the telephone is equipped with a speakerphone, press
the Speakerphone button.
The green LED lights.
You hear a dial tone.
Automatic Callback
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