Scenario: You have several phone numbers on your ATT wireless account; phone number A is eligible for an upgrade, but you want to use your new iPhone 5 with phone number B. Your pre-ordered iPhone 5 comes in the mail, you connect it to your Mac, and the phone immediately asks you if you want to confirm phone number A; it also tells you that, if you are planning to use the phone with a different phone number, just go ahead and confirm phone number A, then call AT&T to swap them. The same instructions appear if you open iTunes 10.7 after connecting your iPhone 5 to your Mac. Problem: If you follow those instructions, then phone number A becomes permanently associated with the nano-SIM in your new iPhone 5; you will then have to go to an AT&T store and purchase for $25 (or angrily demand without charge) a new nano-SIM which can be installed in your iPhone 5 with phone number B. Not only that, but the phone on your account that had phone number A is now dead, and whoever has that phone will also have to take it in to an AT&T store and purchase (or angrily demand) a new SIM, which can then be installed in that phone with phone number A (assuming the iPhone 5 has already been switched to phone number B). In other words, following the instructions on your new iPhone 5 or on iTunes 10.7 deactivates one of your phones and forces the purchase of two new SIMS for $50 before you can start using your iPhone with phone number B and your other phone with phone number A. Solution: What is maddening about this problem is that, if--instead of following the instructions and confirming phone number A on your new iPhone 5 before calling up AT&T--you call up AT&T technical support, they will tell you that they can do everything you need over the phone; you simply pull out the nano-SIM, read them the serial number, and they associate phone number B with your new iPhone, leaving your other phone associated with number A without interruption of service. But if you first confirm phone number A before calling technical support (as instructed), there is nothing technical support get do for you, other than apologize and maybe give you a $50 credit for the two SIMS you will have to purchase. Additional problem: At least one AT&T technical support person (contacted via online chat) was under the mistaken impression that, using iTunes 10.7 to activate the new iPhone, you will be given the opportunity to activate it using any of your AT&T phone numbers. That is not the case: you will have to call AT&T to make this happen (or get the iPhone activated at an AT&T store.) This seems to me a major screw-up that will inconvenience a considerable number of AT&T's wireless customers who upgrade to the iPhone 5 but want to use it with a different phone number.