I have a couple questions about the Gevey unlock. I checked their website, but there isn't much there in the way of FAQ's. Anyway, I have the opportunity to get a 4s from a buddy of mine. It's a Verizon phone and I'm on AT&T. If I buy the Gevey unlock will that allow me to use the Verizon phone on AT&T's network? Which Gevey SIM would I need? Do you have to activate the new SIM and transfer your service, or do you pull it out and put your original back in after the unlock? Thanks!