BBC: Why South Koreans are fleeing the country's biggest social network (10 October 2014)

"[...] The exodus has proved a boon for another chat app - Telegram Messenger - an encrypted messaging service based in Germany, with no servers in South Korea. The company behind the app, founded by the same people that created Vkontakte, Russia's largest social network, says 1.5 million new South Korean users have signed up for the service in the last seven days.

Unlike Kakao Talk, Telegram Messenger offers a "secret chat" option, using end-to-end encryption. The technology means the company is unable to decrypt any of the messages itself, so couldn't hand over information about its users, even if requested.

One South Korean newspaper reports that Kakao defectors have developed a wry greeting when finding each other on Telegram, saying simply: "Welcome to exile."

(Reporting by Sam Judah and Thomas Poole,
http://www.bbc.com/news/blogs-trending-29555331)