Well as far as idea goes, here's another one .

How about we write a watchdog process which for a boolean value from a server(http or ftp) every few minutes(we can set the time) and
then if the value goes to 1, the device just clicks a picture from the front cam, save the gps coordinates and send an sms to a specific number.

That ways, once we have the phone number of the (new simcard of the theif) we can track it. also we will have the gps coordinates. We can set up the app to keep sending sms every few minutes with updated gps coordinates

Just an idea...

Note: That boolean value can be set by the owner by just logging into the server from any internet connection.