I have a samsung SGHG600 that is unlocked. It works with sim cards from the US, S'pore, India, Guatemala, why will it not work with a sim card from a korean telecom provider? I am in Kore. The sim cards I use in those places are prepaid numbers. the sim card I have in Korea is with a provider.

Cell Phones - Samsung - SPH - UpStage SPH-m620 Cellular Phone