I have an iPhone 4S. Mainly used In the states on Verizon and scour for WiFi when visiting abroad. At least, that's how it went with my iphone 4. Now I'd love to pop in a SIM card of a different carrier when I'm abroad but am wondering if I have to be unlocked for this to work. I remember hearing that at one point all iPhones were unlocked but not sure if it's true. If I do need to unlock is this a jailbreak thing? I'm familiar with JBing but not unlocking, If it makes a difference or is of general concern.