A few months ago, Facebook was reported to be testing SMS integration in its Messenger app for Android. Now, that feature is officially live. It's entirely optional, so you'll need to enable it. To do so, head over to Settings in the Messenger app, select "SMS" and then choose "Default SMS app." This means all of your text messages will be sent and received on the Messenger app. Your SMS conversations will be in purple to differentiate them from the default Messenger blue.