I know that AT&T keeps track of all the iPhone IMEIs in the US, since they are the sole carrier. So, if you buy a used iPhone, there is a 100% chance that AT&T has its IMEI and whenever it sweeps the network will see you using it and tack on the extra data charges.
My question is what happens if you buy an iPhone in Canada and unlock it and use it on AT&T? The 3G should work since both countries use the same bands, but will AT&T pick up on the fact that I am using an iPhone? Does Roger share its iPhone IMEIs with AT&T and vice-versa? Or, is it more like a credit card, where all iPhones start out with the same (or contain) the same few digits which identify them as iPhones?
Thanks, any input is appreciated. This is just a thought, my inner hacker had.