NEC DS2000 Feature Handbook page 104

Extension Locking
At a Super Display Telephone, you see:
6. Press
To unlock an extension (and clear their PIN number) from
the attendant's phone:
1. Press
2. Dial
At a 22- or 34-Button Display Telephone, you see:
At a Super Display Telephone, you see:
96
EXIT
.
.
You must have a PIN number entered for your
phone to be able to use this feature.
.