Viber

http://www.viber.com/en/
https://en.wikipedia.org/wiki/Viber
https://twitter.com/Viber?ref_src=twsrc%5Egoogle%7Ctwcamp%5Eserp%7Ctwgr%5Eauthor

Video
https://www.youtube.com/watch?v=-MQw1HtawK0