http://www.stormcam.org/gprs-vehicle/

Can someone explain to me GPS?
I'm looking to buy a GPS tracking device. Here's one I found that the sounds Property Type: I do not understand http://cgi.ebay.com/Mini-Realtime-GPS-GSM-GPRS-Personal-Tracker-Tracking_W0QQitemZ170404863554QQcmdZViewItemQQptZGPS_Devices?hash=item27acebde42 how it works. It says to insert a SIM card in the device. Does that mean you need a phone number that assigned? Another method would be better for me, instead of having to call every time it is through GPRS. Do not know what it is, how it works, how to set up, or if it costs something. Ideally, I'd like something that you can put in a vehicle, which transmits to a computer at all times, indicating how long a vehicle is stopped wherever he was arrested less as well. Whoever takes an SD card I could not exchange be great, too! Any ideas on a cheap model that work this way? It must have a very self long, too.
Whatever you are looking for you on the slopes. This is for people who are worried they might get kidnapped or something, so that people can find you. My brother uses a Garmin Gps for his truck. It shows him where he is, he has a car charger (and a long battery life), he did not invoice Monthly, and only $ 50. particular model? Nuvi 205
Demonstration Video GPRS Tracker (Buy or Rent)