Hi,does anybody know korea now using 2G or 3G phone?

Answer 1

They are using 3G phone.
It's not called 3G over there, it's called CDMA phones.
It's the same at Japan.

Answer 2

Korea is second country in the world to commercially introduce 3G into market.
Current network is mix of 2.5G and 3G but majority is still 2.5G.
3G+ service, which is 3.5G is starting to roll-out recently.

2G, 2.5G and 3G is about network capability.
CDMA and GSM is a method to access to network.

In conclusion, 2.5G or 3G CDMA phone can be used in Korea.