Viber is a smart app, which helps you communicate with your contacts for free. All you need is a data or wi-fi connection on your phone. Viber allows you to text, call, and send photos and video messages worldwide for free to over 200 million users who are already registered on it.
Simply put, your phone no. becomes your id, and you do not even have to rebuild your directory. Viber does it for you, by scanning all the phone nos. in your directory and automatically identifying those who are connected to Viber. So, once your no. is registered (there is a simple process for that) you are ready to go !
Viber has excellent sound quality, you can have conferences with upto 40 people at a time, you can share your locations and also send interesting emoticons in your messages. Push notifications guarantee that you never miss a call or message, even when Viber is off.
I did find a minor conflict with my Bluetooth wireless headset, but I will figure it out soon. All in all a great way to communicate especially with your contacts who are overseas !