Now I have no idea about this but I was wondering... If I were to get a t-mobile or at&t prepaid sim card from one of those prepaid phones you buy at walmart, take it out and put it an unlocked Nexus One, I would get signal right?(3G or edge if so?) Would it know how many minutes you had or is it impossible to add minutes and calls would be rejected? I'm confused on this. If it did signal, could I just use google voice for all my calls and texting and never have to pay for more prepaid minutes? I'm clueless on how this would all work out so I may sound like an idiot but if this worked out I'd think it would be pretty awesome.