I've noticed this in the past when I was considering the 3GS, and I got the same message today. I am currently with T-mobile on a family plan and was playing around with setting up a family plan through apple's site (wanting to order 2 iphones). After I submit all my info to determine eligibility, it tells me that I have to go to the apple store to set up my family plan. Does that have to do anything with buying multiple iphones at once? Do I have to buy the Iphones through ATT, instead of Apple?