you are redesigning lojack? the only benefit i see is that you say no subscription, but i don't think so, you need a phone plan on that phone, so unless you are using it to replace your current cell, that's a subscription cost, and you can't really use it as your cell, because then you would not likely leave it in your car when you park. I suppose it could be used to find a lost or stolen purse, or the phone itself, but otherwise, i see no purpose. also, all new phones are traceable to location, some use it for built in GPS nav. others just use it to transmit your location when you call 911. so you could just add a service via your phone company which allows you to trace your phone on demand. no new hardware required.

Only high-end phones currently have built-in GPS; other location methods are too approximate (hundreds of meters) to be useful for stolen-car tracking.About signing up to a service: OF COURSE you have to use a dedicated SIM in the phone... but I guess (I do not have any "real" GPS antitheft) it's the same for commercial GPS antitheft, but buying one of them you ALSO have to subscribe the location service, which provides access to data.You actually do not need such a service: all software needed to track the car can be implemented on another phone (there are plenty of SW which show google maps on phones).

You still need mobile service of some sort.

It could be done with an all-in-one programmable smartphone, or with a separate bluetooth GPS.

Transystem makes a GPS/GSM tracker.

@classicsatA lot of companies build and sell GSM/GPS trackers. None of them costs less than 300-400$ !!! Even a module to be inserted by hand into a circuit costs 150$!

I just read that the GPS chip that's in the new iPhone costs under $5. As for the service plan, the FCC requires that service providers offer people a phone that only dials 911 and charges only a dollar or two for that call. That requirement could be extended to incorporate replying to a call with location data. So I'm strongly in favor of this idea.

I just added my project to Google Code, for anybody who wants to use/extend/port it. ;-)http://code.google.com/p/lc-cartrack/

Currently it works on nokia phones supporting python (Symbian series60). Would be glad to see it ported to other languages/platforms.