How to disable a STOLEN mobile phone?
To check your Mobile phone's serial number, key in the following Digits on your phone: *#06#. A 15-digit code will appear on the screen. This number is unique to your handset. Write it down and keep it somewhere safe.
If your phone gets stolen, you can phone your service provider and give them this code. They will then be able to block your handset so even if the thief changes the SIM card, your phone will be totally useless. You probably won't get your phone back, but at least you know that whoever stole it can't use/sell it either. If everybody does this, there would be no point in people stealing mobile phones.