If you are looking for a Skype or FaceTime alternative, Viber is finally giving you that on your phones. Video calling is making its way out of Viber’s desktop application into iOS and Android apps. It supposedly works even if the connection strength isn’t that good. Viber said you would need to make voice calls first before setting up video calls. Once in a video call though, you still have the option to send text messages or transfer the call to your desktop if you want to. iOS users need to have an iPhone 4S with iOS 7 or later. Meanwhile, Android users need Android 4.0 or later device, at least 1.3-megapixels for the front-facing camera, and 1.5GB of RAM or more. Both need to have Viber 5.0 or later versions as well.
Source: Viber