I have a factory unlocked iphone from EUROPE. I'm visiting back home in THE us for two weeks. What would I need in order to be able to us the iPhone over here wihout paying international costs?
In theory yes, though if you go down the PAYG route the default APNs won't work as GoPhone isn't supposed to be able to have Data on the iPhone. You'd need to create a custom profile (Google search to find how) in order for data to work. For calls and SMS just put the AT&T GoPhone SIM in and you're good to go