And it now seems the hugely popular messaging app has started rolling out the feature to a select number of users, according to Dailymail UK report
A screenshot, posted to Reddit at the weekend, reveals how the Calls tool looks on a Nexus 5 device running Android Lollipop.
In the image, a new tab has been added that shows 'Calls', in addition to the existing 'Chats' and 'Contacts' options.
Users can then open the Calls tab, select a contact and make a voice call using an internet connection.
This is similar to how Skype connects web-based calls, a service known as 'voice over internet protocol' or VoIP.
In December, Dutch site AndroidWorld uncovered clues about Whatsapp's voice calling feature while studying the app's test code.
Expert Sander Tuit then extracted layout files, images and text from the raw code to create a series of mock-up screenshots.
The latest grab was posted to Reddit by user pradnesh07, although it has since been removed because it contained personal details.