Hi, I am thinking of getting an unlocked iPhone 5s so I can swap the Micro SIM card when I travel international instead of paying the equivalent of a mortgage payment to AT&T. I currently have an iPhone 5 with AT&T and it states on the Apple website that an unlocked iPhone will come without a micro SIM Card and that I would need to purchase one. My question is: Can I just take the micro SIM card out my iPhone 5 and put it in the 5s and have it work while in the US? Has anyone done this? Thanks!