I got a question. I am planning to get my iPhone 6 at the Apple store and want to use it on AT&T. Can I buy at the apple store then activate over the phone with AT&T? I hope I don't have to go into AT&T too as I'll be fighting lines twice. Would I need a sim or would the phone come with one? I am a current AT&T customer fwiw just never bought unlocked so this is all new to me.