Out of the many instant messaging apps on the app store Viber is one of the most used and preferred Android apps available. It is totally free. Although first released only for the iPhone and in direct competition with Skype, Viber vowed to provide users with the best experience of video calling. Viber: Free Calls & Messages is an awesome application for Android that lets you chat and call friends from your Viber contact list completely for free in case you have a stable Internet connection. This is an indispensable tool if you want to st. Viber is a well known VoIP service which allows you to call and send instant text messages to your contacts without spending a cent of your money. This voice over IP application for Android performs voice calls through your internet connection, so it doesn't affect to your phone company's calls rate, but your data plan or your WiFi connection when available.