Find "Call barring"
Press the menu icon.
Press Settings.
Press Call settings.
Press Call barring.
Change barring password
The current settings will be displayed.
Press Change password.
Press Change password.
Key in your current barring password (default is 0000) and press OK.
Key in the new barring password and press OK.
Key in the new barring password again and press OK.
Exit
Press the Home key to return to standby mode.