You might be asking why there is no mention of Voice Calling in the changelist. The answer is rather simple, we're told. The feature is not yet active. But you can see a pop-up that requests access to the microphone on your iPhone, and specifically mentions Voice Calls. Simply go to Settings > Privacy > Microphone > WhatsApp > and flip the slider to off. Go back and open the WhatsApp messaging app, and you should see the same pop-up pictured below.
WhatsApp was purchased for a whopping $19 billion from Facebook. The service is free for the first year and 99 cents each year afterward. And with the latest update adding a ton of new features including improved location sharing, the ability to share slow motion video from the Apple iPhone 5s, the capability to trim video before sharing it, and Voice Calling (when activated), we could see more new subscribers get added to the 600 million that currently use WhatsApp.
Pop-up message that appears if your iPhone doesn't give WhatsApp permission to use the microphone on the phone
source: NDTVGadgets via 9to5Mac, Gizmodo