An AT&T rep just told me on the phone that I need to pre-order the iPhone 4S by calling them if I want to do an upgrade swap. They told me NOT to order online. They said once I order the phone online using another line on the family plan -- I can never use that phone on a different phone number. It is locked to the number, even if it wasn't activated. Is this true? This goes against what I've read here, even on the MacRumors iPhone Upgrade Guide. EDIT: 3rd time's a charm. Spoke to my 3rd rep of the evening who was ON POINT and knew everything. She said it's real easy and happens all the time. Order the phone on the eligible number and when I get it (before activating it in iTunes) call them up and then they will switch the number and you're good. The eligible line will not be affected at all except they renewed the agreement for 2 years.