I'm moving to HK January 2nd for two years and I'm curious if the iPhone 4S you get from SmarTone is unlocked? I realize if I get one through them I'll be tied to a two year contract, I just need to know if they're locked to the carrier, or if when I travel I can put in a SIM card from the place I'm traveling in and have it work. In the US, my iPhone is locked to AT&T, but I've heard that's not the case in HK and just want to confirm. If they are locked, then I need to buy an unlocked one here before I leave for HK. Thanks.