@Phil0124 @Meg St._Clair That is actually not true. You can now use an unlocked ATT iphone 6 on Verizon. It used to be that Verizon would only allow a limited number of phones on their network. (a few sprint phones) It used to be a pain. Now, since the phones are much more universal, they allow much more on their network.
Two things:
1. I use an unlocked ATT iphone 6 on Verizon. Yes, it works!
2. If you goto Verizon's website, and check to see if the device is eligible, and put in an ATT iphone 6, it will tell you that the device is eligible to be activated on their network. Almost all Verizon employees haven't a clue about this, even Verizon store managers AND Verizon Store Owners, and they will tell you that you can't, but that is only because they don't know about this.
Simple test. Put a Verizon sim in an unlocked ATT iphone 6. It works. but you should try it first yourself! Then you will know.
As far as the original post about Korea? I don't know. I don't live in Korea. ;-)