Using an iPhone 4S in South Korea My brother will soon be going to South Korea to teach English and he is wanting to make sure that his phone will work properly with a local carrier. The phone is SIM unlocked (we verified it with an Orange UK SIM card that I picked up last summer in England). So, does anyone know of a South Korean carrier that supports iPhones?

The iPhone 4S is from Sprint in the USA originally and they unlocked the GSM SIM slot for me because I was going to spend some time in the UK.

Will this GSM-unlocked CDMA phone work with any South Korean carriers?
It will work on KT (they even sold the 3GS which wasn't CDMA), and possibly others.

He may need to get the IMEI registered with the network before the SIM will work in it though as they are very protective over their networks (this was true up until 2010 at least, although they may have become more relaxed on this since then).