I have an iPhone locked to AT&T. After updating, if I don't have the AT&T sim in it, then it won't activate. (I'm not talking about unlocking here). Well, I cancelled my AT&T account and my iPhone is unlocked on 3.1.2 If I were to upgrade the firmware (which will require reactivation) will the AT&T sim still activate it? edit: I know about "hacktivation" but I would like to keep my push notifications.