This is a neat little trick that should work with most phones and phone service provider. You simply enter a code in your mobile phone that reveals the unique serial number of it. If your phone gets stolen you report the theft and the serial number to your provider and they have the means to make the phone useless. That means no one will be able to use it, at least not for phoning.
The code is: * # 0 6 #
The fifteen-digit code is the unique serial number of your mobile phone. Write it down, it´s your IMEI Code. When someone steals your mobile you report the theft and your IMEI Code to your service provider. Most providers will ban that serial number making the phone useless.