Samsung's IM app can take over SMS and MMS duties, but only in a couple of countries for the moment
Hot on the heels of Google Hangouts growing SMS and MMS support, Samsung's ChatON messaging app has also been updated with the ability to serve as your sole SMS and MMS app. The new feature, which at present is only live in Germany and Brazil, combines text conversations with ChatON messages, and also merges your phone contacts into your ChatON buddy list. The app has also been updated with a new badge added under the ChatON icon, allowing users to see the number of unread messages.
While ChatON is bundled on Samsung smartphones, the app supports a wide variety of Android phones from other manufacturers, meaning that like Hangouts it can presumably take over SMS duties on non-Samsung phones too. We haven't been able to get any one-on-one time with ChatON's SMS integration just yet, but it's unlikely this feature will stay exclusive to a couple of countries forever. In the meantime, if you're in Brazil or Germany and want to take this new functionality for a spin, hit the Google Play link above.