I have T-Mobile and want to buy a phone using the iPhone Upgrade Program, but it says this can be done in stores only. I remember last year there was a page where you could select your phone and carrier and then make a reservation to pick one up at the Apple Store if there was availability. But this year, that page seems to only come up if you're ALREADY in the IUP. How is a T-Mobile customer supposed to sign up for the iPhone Upgrade Program? Do we just have to walk into stores and hope there's availability?