I do have it installed it in one of my car.
About the questions you all are asking
*It is a Real useful device as there is no monthly charges; one time cost.
* It callls 4 cell numbers in order of priority i.e you can give the number of the person who primarily drives it and then ur borther's number , ur father number. cousin's... Atleast one out of all would definitely pick up and would listen to the alram warning which is played when the car calls u.
* If someone steals ur car( God forbid ) u can turn the engine off by a single phone call, lock the doors, cut the fuel supply.
* Lets suppose someone snatches your cell phone or some other belonging, u can also MAKE A PHONE CALL from ur car just like ur personal cell phone and inform others about your situation and location
* If there is no service ... your command would be excuted whenever it catches the signal again.
* YOu dont have credit in ur cell... u can call from ur car... and if your cellz out of battery..you could be reached at your car number during your journey.
* You can listen to the conversation in the car secretely( a plus if your friend has taken your car for a date lol )