I'm not familiar with the exact device, but strongly suspect the cell phone simply serves as the internet link. Early car trackers had integrated cellular radios, but that can't be cheap.
>> Early car trackers had integrated cellular radios, but that can't be cheap
My TomTom 5000 SatNav, which I bought for like $200 has a permanent connection to the internet in all countries of the world with no monthly fee. It has an integrated SIM card and TomTom just paid some fee so that it can connect to the internet and get traffic updates wherever I am in the world. An even cheaper Kindle 3G also had that. So I guess it must be relatively cheap.
Well, my ISP provided me with a very fancy fibreoptic router and a TV box with a terabyte hardrive which I am pretty sure cost them pretty penny yet I haven't paid anything for either of those things. They make money off me every month though, just like an insurance company would - they give you a fancy box for "free" and make money off you selling you their service.