[EyeB]

on pagers you can do that as well... i mean limit who can call it.
since pagers are setup with a phone company, just call them and say only let this number page it

I'm not sure how to do this, but you could probably rig part of the electrical wire to a usb port (so you can leave smoke thing open for other things to charge) and plug phone into that consistantly. This way you'll charge it when engine is on and battery wont be a concern. In the winter time it'll cause phone some problems because of freezing temperatures though.

but why not just buy a remote starter for car if you want this? I mean I've seen people rig phones to doors to unlock via bluetooth signal but they have remote starters for cars already, and fairly cheap :S at least for same price as a tp2 would go for

edit: if you are using it via bluetooth, you wouldn't need text message (no monthly fee on phone) to cut down on costs... the range is a lot more limited though.