Facebook Messenger lets users text, voice-message, send video or photos instantly, or call contacts from their mobile devices.
One can register and use messenger even if he doesn’t have a Facebook account. This is a very good app with good quality audio and video calls.
Recently they added a game in the app. This app is updated every couple of weeks. But, the only thing I hate is it takes a lot of memory. The chat head thing is cool. It serves the purpose aptly. I like this app and I think almost every one who uses fb has this app.