I was told by the AT&T rep. buy the phone from apple or where ever (using the eligible line) They use this for verification for new 2year commitment.
Once you get the phone plug into iTunes and it will ask for your phone number that you want associated with the phone. The sim cards in the iPhones are blank when they arrive and are not attached to a account. iTunes connects to AT@T and assigns a number at that time. They do this for security reasons. makes since to me because anybody that gets hold of the phone before activation will be able to use your phone account and deactivating your other phone. Hope this helps and explains why it SHOULD work. HA HA
She did say if for some reason you don't get the number in iTunes Don't activate the phone first call or come into the store and they will do the transfer.