Facebook it seems is upping the ante as voice messaging services Skype and Viber will soon have to grapple with some stiff competition from the company-owned WhatsApp. How you ask? The mobile messaging app is gearing up to introduce voice calling service for its users - possibly for free!

Reports suggest that the updated version of WhatsApp will offer support for the voice call feature. WhatsApp's CEO Jan Koum had let on at the MWC 2014 that voice calling would make its way to the app. The update for the service was slated for Q2 2014, but is yet to make its way to users.

However, alterations in the UI of WhatsApp, as revealed by leaked images of the same, seem to suggest that the groundwork for the impending feature is being laid.

"The leaked images of the upcoming user interface shows that the app has been enabled with other language translations which will be displayed at the time a person receives a call via WhatsApp," notes a thefusejoplin.com report.

Currently, the translation feature leaked in April this year) that is accessible on the latest WhatsApp version (also points in the direction that the voice calling feature is set to arrive soon. The leaked images also reveal that app will imbibe buttons for speakers, muting, message and ending a call.

With the voice calling option available for WhatsApp, users will not only be able to chat with those on their list, but also call them up without a fee being administered. This factor may give WhatsApp an edge over rivals Viber and Skype which charge 1.9 cents and 1.7 cents per minute, respectively, in the U.S.

Another advantage WhatsApp would have over Skype and Viber is that by comparison, it uses less bandwidth. While there are often delays (few seconds) in calls made via Viber or Skype, the fact that WhatsApp is highly optimized for voice calls would mean that there would be no delays.

Initially, the voice calling feature for WhatsApp will only be available for iOS and Android devices. However, BlackBerry and Windows Phone users need not get disappointed as the feature will also make its way to these platforms.

However, a major concern with WhatsApp would be privacy as anybody on the contact list has access to the user. Moreover, in the long term, offering free international voice calls may work out to be an expensive proposition for the company. In the event Facebook looks to deploy ads to generate revenue, users may be put off.

A possibility exists, that the voice calling option for WhatsApp remains free for a year and then users are charged a subscription fee.