I'm very glad to find this thread.
My dad lives in Wisconsin, he has a 4, is due for an upgrade but only uses the phone to text and call so he has no interest. I am able to use his upgrade.
I live in Florida. I have a 5, can sell it to nextworth.com for $451, the 5S (64GB) w/upgrade is going to be $399. Not a bad deal at all.
If I go into the Apple Store and purchase over the counter, they apparently HAVE to activate it on the spot.
If I buy online, I activate at home via iTunes. So the question I have is: if I swap the SIM card before I activate the phone initially, will that activate the phone 5S with the old 5's account, and then I toss the SIM that it shipped with? I don't want to activate the new phone and have my dad's current phone de-activate on him.
I know that if I was on my parent's account, I could just "cross-upgrade" or whatever it's called within the same "Family" account but I haven't lived at home in years.
I guess I am thinking I could just buy the phone using his account info, have it shipped to me, and then call AT&T to activate the phone, but I dunno how this will go over with them. Also I don't know if Apple will ship to MY address when the upgrading account's billing address is my father's. I seem to recall that you have to initially place the order and have it shipped to the billing address on the ATT account, but then you can go into the account and update the order with a new mailing address.
Does anyone have any thoughts or input on how to make this work?
Edit: Nevermind, AT&T rep online and I actually had a lovely chat and reassured me what I wanted to do is no problem, and I have a pdf of the chat should I need to prove it. Sounds like I just have to order from Apple, have it shipped to my house, and activate it to my number and not my father's. His service won't be effected and the upgrade price is what I pay. "Cross upgrade" accomplished...
Now I just have to see it to believe it.