Me and my dad currently have phones on AT&T. My dad's coworker offered to give his "unlocked" iphone 3g to my dad as a gift. My dad is skeptical though because he's not sure if At&t will force him to get a data plan. He's fine with just using wifi and doesn't need data. Will At&t force him to get the data plan? (My dad's phone has data blocked btw, if that info helps)