In this Aug. 20, 2012 photo, a woman opens Kakao Talk, a South Korean mobile messaging app with more than 60 million users, on her smartphone in Seoul, South Korea. A handful of smartphone apps that began as basic instant messaging services have amassed several hundred million users in Asia in just a couple of years, mounting a challenge to the popularity of online hangouts such as Facebook as they branch into games, e-commerce, celebrity news and other areas.