1 - Set a password on your device (Options -> Security Options -> General Settings). You then have to enter a password to unlock/use the device.
2 - Disable 'dial from home screen' (Phone icon -> Options -> General Options) and you can then press the K key from the homescreen to lock the keyboard. Then you just have to press 'Unlock' to use the device again.
__________________ No longer a BES Admin, but it was fun while it lasted!