Here's the deal. I'm on a family plan with 3 people. Father, me, and brother. My father has a crappy black razr from a long time ago, me and my brother both got the 3gs the day it was released. My brother is the primary line on the plan, so he's elgible for the upgrade.. My father doesn't care about his phone so he's elgible for an upgrade as well... but since i'm not the primary line and I just got my 3GS, i would have to pay $399. My father said I could go ahead and use his upgrade... can I go in to att and use his upgrade without ever activating the phone on his line? Obviously we do not want to have the data plan on his line, and I would like to keep the unlimited data on my account... Is this possible?