You can use the lock feature to prevent unauthorized people from making outside calls from your extension while you are away from the extension. The user of the first extension on the system can unlock extensions without needing to know the code used to lock the phone. They can do this using Feature 22.
To Lock Your Extension
1.Press Feature 936.
2.Dial a four digit code using the 0 to 9 numbers .
3.Redial the four digit code.
To Unlock Your Extension
1.Press Feature 936.
2.Dial the four digit code you used to lock the extension.
To Create a Station Lock Button
1.At the phone press Feature *3. Program Ext: is displayed.
2.Press the button that you want to edit or enter the button number to select the button. The current setting of the button is displayed.
3.Dial Feature 936. The current setting of the button will now be set to Station Lock.
•To finish, end the call or press the 
Release button.