Find "Call Barring"
Press Connect.
Press the Menu key.
Scroll to Options and press the Navigation key.
Scroll to Call Barring and press the Navigation key.
Change barring password
Press the Menu key.
Scroll to Change Password and press the Navigation key.
Key in your current barring password (default is 1919) and press the Navigation key.
Key in the new barring password and press the Navigation key.
Key in the new call barring password again and press the Navigation key.
Exit
Press Disconnect to return to standby mode.