Purchase a security system (ie Burglar alarm) which has GSM dialout and 24 hour panic button facility. Make sure the system has a standard input for the panic - you don't want one of those silly systems which puts "panic button facility" on the label, and then expects you to push two keys on a keypad. Wire up a simple pushbutton which you can buy at radio shack if you are extremely quick. You may have to put an End-Of-Line resistor across the switch - consult someone who knows if that is the case. The rest is pretty straightforward. (GSM dialout means it calls your mobile/cell, 24 hour panic means a button which will send a signal even when the alarm is disarmed)

Sapphire has a lot of uses besides the purely cosmetic - Perhaps the worlds biggest electronics innovator actually is targeting a future electronics requirement - Better RF, better sensors