WhatsApp has announced that more than one billion users will be able to make video calls on iPhone, Android and Windows Phone devices "in the coming days." And to work out all the kinks, WhatsApp has been beta testing this feature over the last few months. This is a highly anticipated feature because WhatsApp users have been requesting it for years.
When you receive the WhatsApp app update with the video calling feature, you can try it out by tapping on the call icon at the top right corner of a chat. Tapping on the "video call" option starts up a video chat with that WhatsApp contact. If you have not received the app update yet, then WhatsApp will simply make a phone call to that contact instead of presenting you with both options.
As you are using the video calling feature, you can switch between the rear- and the front-facing camera of your device. There is also a mute option if you do not want the receiver to hear what is being said through the microphone. And tapping on the red phone icon hangs up the call. [forbes]