Remote lock
You can lock your device from another device using a text
message (5-20 characters long). To enable your device to be
locked remotely, and to define the lock message to be used,
select
>
Settings > Settings > General > Security
and Phone and SIM card > Remote phone locking. Enter
the content of the message, verify it, and enter the lock code.
To lock your device, send the lock message as a text message
to your mobile phone number. To unlock your device, select
Unlock, and enter the lock code.