WhatsApp appears to be setting up a "call via Skype" feature5
But based on a string of code, WhatsApp plans on offering a feature called "Call via Skype." Other features confirmed by the string include Call Mute, Call Hold, Call back, Call me in X minutes, Call back message, Call Via Skype, Call Notifications and Separate screen for call logs. We've also seen images that supposedly reveal what a phone call using WhatsApp will look like.
Also, a "Driving Mode" for WhatsApp also appears to be in the works. This would be akin to placing a Do Not Disturb sign on your phone while you are behind the steering wheel. Additionally, there might be a feature that will allow WhatsApp to read your messages to you while you are driving.
Thanks for the tip!