WhatsApp enabled and tested their Voice calling feature to a limited number of users initially and later rolled out to all users and other operating-systems. Leaked screenshots by an German site MacerKopf suggest that popular messaging service is all set to launch video calling feature for it's users.
WhatsApp has over 900M+ users which it acquired in a short span of just 6 years, the free video calling feature on this popular IM service is surely going to give competition substantial jitters of the likes of Apple (FaceTime), Microsoft (Skype), Google (Hangouts) and mobile-carriers.