!! I use Kakao Talk, Line, and WeChat :) Kakao Talk is really popular in Korea. ^^ It's easy to make an account too.

Kakaotalk and Line are two very popular apps a lot of Koreans use to communicate with each other. Both are free and as long as you're connected to wifi, you can even call each other for free! (when my best friend went to Korea for a month we used Kakao to talk every day)

Most of koreans use 'kakao talk' app. This is very common and popular. So some foreigners who want to talk wth korean download this, add koreans on list and talk together.

I don't understand your question. :[