Hey guys, I really need ur help. I bought a locked ATT iphone 4s... the guy who sold it to me took out his sim card. When I try to activate it with a prepaid ATT sim card inside, it tells me to put in the billing zipcode and last 4 of the social of the person who sold me the phone. Is there a way to even activate the phone without this info? Does anyone know? ( Thanks, Janna.