There is a glitch with the Verizon iPhones you need to be aware of. If they see a CDMA network, they will lock on to it even if they can't roam on that network. People have complained about not being able to use their Verizon 4s in Taiwan, China, Ukraine, Russia, and India because of this. I would go to the CDMA Association website (cdg.org) and see if there is CDMA where you are visiting. Check out this thread: http://www.flyertalk.com/forum/travel-technology/1278120-verizon-iphone-4s-international-roaming-iss... There are conflicting reports whether you can force the CDMA to the off position on unlocked Verizon 4s with a third party SIM card in it. Also be aware that you will have problems with many roaming SIMs on Verizon because the dual IMSI SIMs (which are partly a US IMSI) don't play well with Verizon's partial unlock. If I were one of these people, I'd ditch the phone subsidy and buy an unlocked iPhone (or Google Nexus).