Viber plans to make it so you can chat too in a future update.

The problem here is that you can't participate in the chats yourself - you can only watch. It has a few celebrities and companies (such as Disney) you can follow to see what people are talking about. Simply purchase credit online at a discounted rate and enjoy pre-paid and virtually unlimited calls to home and mobile numbers. Call any landlines and mobile numbers, whether local or long-distance, even to contacts not using Viber. Viber lets you listen in on public chats with various themes such as Song of the Day or Disney Theme Parks so you can follow topics that interest you. What is Viber Out Viber Out is a voice-over IP (VoIP) service that allows you to call any phone number, domestic and international, at the lowest rates. If limit is exceeded the normal rates apply.

Unused free minutes cannot be taken to the following week(s). I found that the video quality suffers somewhat with a poor connection, so Wi-Fi is the more ideal way to make video calls. VoipDiscount Free Calls are subject to a fair usage limit, measured over the last 7 days and per unique IP address. Video calls are also free so long as both parties have Viber, and will work on a 3G connection or better. This means if you have a friend in London and you're in the United States, you can quickly figure out how much credit you will need for the amount of time you want to talk. What's nice about this feature is that it tells you how much it will cost to call various countries before you spend anything. The app lets you add money to your Viber Out credit with a tiered pricing plan. If you want to call landlines or people who don't have Viber, you have the option to buy what it calls Viber Out.

Viber calling rate