My wife's iPhone on my account is eligible for a full subsidized upgrade. I want to purchase the iPhone 5S and transfer the upgrade since my iPhone 5 is not eligible. From what I understand, I need to purchase the iPhone 5S using my wife's number and then call AT&T to transfer the upgrade to my number. Has anyone actually done this? This will be the first time for me and I want to make sure I do it correctly. What is the correct process so I don't screw this up. Thanks.