Looks promising. Installed it before but nobody was using it. Just installed it yesterday and a few friends already using it. Too bad doesn't support other OS such as BB and Windows yet.

Dear Viber,

Are you like, working for Viber? If yes, then you definitely need to support all the major OS ASAP. Most important right now is for BB, and then WP7 as it is catching on. Anyways, very good app you have here. And you should put a shoutout box or recommendation box on your site so people can drop their ideas on how to make the app better. Cheers bro.