People are wondering how Viber makes money.  One of the way to make money for Viber is to provide cheap viber to phone calls and also normal phones to viber calls . how Viber makes money Below is what Viber had to say about how this subject.

There are multiple options available to us – we are yet to decide exactly how. What we do know is how we are NOT going to make money: 1. We will NOT charge for the app 2. We will NOT charge for Viber to Viber calls 3. We will NOT charge for Viber to Viber texts 4. We will NOT advertise on the VIber app. And needless to say, we will not sell, rent or in any other way abuse your data. I hope this helps. Talmon (Viber Media)