I'm in the brainstorming phase to develop a GPS car tracking system requested by a customer. I myself know the directions to build some GPS system to mobile phones and etc. But sincerely I don't know how to start in that project. That is the scenario:

1) The cars will get a device with a SIM CARD that will emit GPS signals.
2) My customer will in any place (home, work, etc) with a web connection will see in the map where the car is located.

For me, I have not problems at get the GPS data, convert to usable info and show the position in some map system (like Google Maps or MS Bing Maps, by example). My problem is, how I do to retrieve that "GPS Signal" from device in the car? I will need some kind of "Receiver Device" connected to a web server machine in order to my application to consume that data? Or "automagically" my sodtware will receive the info from a third-party web-service? Or what?

I thank for any help!