Find "Security keyguard"
Press the Navigation key.
Scroll to Settings and press the Navigation key.
Scroll to Phone and press the Navigation key.
Scroll to Security keyguard and press the Navigation key.
Turn use of phone lock code on or off
Highlight On or Off and press the Navigation key.
Key in the phone lock code (default is 12345) and press the Navigation key.
Exit
Press Disconnect to return to standby mode.