The SMS ringtone "Gado" in Korean dramas.

The ringtone of SMS "Gado" is the cough that Ka Kao talked about, which is equivalent to QQ.

Ka Kao is a free chat software from South Korea, and China Tencent is its largest shareholder. It is similar to QQ WeChat chat software, and can be used as an application for communication between smartphones such as iPhone, Android, WP and BlackBerry. This application manages friends through the actual phone number, and with the help of push notification service, it can quickly send and receive information, pictures, videos and voice intercom with friends, relatives and colleagues. Similar to QQ in China, even if your friends are not online, they can receive your Ka Kao talk message, just like texting.