My local AT&T store is out of iPhones. The Apple retail stores in my area have many in stock according to http://apple.com/retail/iphone Here's my problem: I need a family plan with at least 1 iPhone and 2 normal Cingular phones. Can I pick up the iPhone at the Apple store, wait till I go to a Cingular store, sign up for a 4 phone family plan, then activate my iPhone at home? I'm assuming I'll need to sign up for an iPhone plan first before Apple retail allows it to leave the door. Can anyone clarify this for me?