I travel extensively and my colleagues have all become highly dependant on the iPhone. That is why when I found out that one had bought an unlocked iPhone 5 in Hong Kong and brought it back to Canada only to find after inserting his Canadian SIM card found the phone would only roam. After spending time with apple support it was determined he would need to purchase a separate iPhone for use in North America. After referring to the apple store, I noticed the 4S shows only one model and that model specifies "world phone" while the 5 shows three models without any "world phone" designation. I think anyone hoping to swap SIM cards when travelling should be wary purchasing an iPhone 5 and consider sticking with the 4S.