AT&T Call Management System Supervizor's Manual page 139

CMS Telephones and Telephone Programming
For the MLX telephones, dial the 3-character code [Feature] [0]
[0] .
In programming mode, both types of telephones ring every 5 seconds
to remind you that you are programming and that you cannot place or
receive talk.
Without lifting the handset, touch the button you want to program.
3.
4. Dial the feature's programming code and any other numbers required.
See the following chart or refer to the "Quick Reference Guides" in the
MERLIN LEGEND Communications System Reference.
If you want to program other buttons, repeat steps 3 and 4.
5.
If you make a mistake when dialing any of the characters, simply touch
the button
numbers.
Leave the
6.
For
For
[0] .
5-32 Telephone Programming
again and redial the programming code and all required
programming mode in one of these ways:
analog telephones, slide the T/P switch to the center position.
MLX telephones, dial the 4-character code [Feature] [*] [0]