NEC DS2000 Feature Handbook page 102

Extension Locking
5. Press
To change your PIN number (if you already have one
assigned):
1. Press
2. Dial
At a 22- or 34-Button Display Telephone, you see:
At a Super Display Telephone, you see:
3. Enter your current PIN number + HOLD.
At a 22- or 34-Button Display Telephone, you see:
94
EXIT
.
.
.