Facebook owned messaging service WhatsApp has reportedly started testing a voice calls feature.

Reports began to emerge when a few Reddit users noticed the new feature, which prompted the posting of videos of the feature on YouTube, reported Mashable.

According to reports, it is a part of the beta testing and other users have spotted the feature on iOS and Android devices.

The voice calling feature functions like Facebook Messenger, WeChat, or Viber. The new chat window shows a phone receiver icon, which is located next to the contact’s name.

Users also found minor changes to the app which included a separate pane for keeping track of voice calls, and notifications for missed calls.

BGR India reported that the call had clear audio and worked without any interruption on 3G networks, and is expected to give competition to normal calls.

During Mobile World Congress, WhatsApp CEO Jan Koum announced that the feature was in the works but he did not give any details.

The company recently announced that its 700 million monthly active users exchange 30 billion messages per day, and recently expanded its service to desktop.