Viber is VOIP app that can be used to make free calls and SMS from viber to viber. It does not require any registration as it integrates with your mobile number. Seven months ago Viber was launched only for iOS but now it has been launched for Android. It has all the features for Android that were present for iOS and even more. It has its own contact list, call logs and can be used as default dialer. Viber already have 12 million users using Wifi or 3G to make calls. Its a must have app. Check out the video.