Just an update the upgrade swap went flawlessly. Took about 25 mins cuz she had to ask some questions to her supervisor but she didn't even need the imei or micro sim number! Sooo happy right now!
Went over fine at Best Buy. They jumped the gun a little bit and activated the phone before AT&T had switched everything. Was on with the rep and everything was fine. Took about 10-15 mins.
There must be something different about the activation for Apple-shipped phone versus AT&T shipped phones versus instore phones. Or, it could just be the the apple-shipped phones weren't meant to be upgrade-swapped till today. At any rate, I had the same problems many had. They correctly linked the IMEI/ICCID to the other line but Itunes still had the original phone number...
Were you able to get it to work eventually? I am on the phone with ATT right now and have made no progress...
The Apple Store I went to today to pick up my iPhone had at&t reps in the store to help with upgrade swaps and what not. It saved me a lot of headache