The Verizon and AT&T models are both world phones that will support GSM frequencies overseas. It's the same chip in each of them. The only difference between the two is LTE bands, for which the Verizon model has more international compatibility. If you are a good standing Verizon customer for over 60 days, they will unlock the iPhone 4s/iPhone 5 and let you use an international sim card while you are away on vacation.