So, my dad has a blackberry (att) and has a blackberry data plan (enterprise) and he can upgrade his line, but I can't. So, I'm taking his upgrade to get an iPhone 4S. However, the Apple rep said he can't do it because it would mess up my dads plan. How so? Can't he just buy the phone, extend his contract 2 years, and activate the phone under my number while giving me a data plane ? ( I have a LG dumb phone now). I don't understand what the problem is? Why would his plan be affected?