Facebook had announced at the beginning of this year that it was testing a free voice calling feature for its Messenger app and now, it seems the testing has been successfully completed. The social media giant has rolled out a service by which iPhone users in the U.S. can make free voice calls to other Facebook users using a Wi-Fi connection.

First to bring out the new development, The Verge reported that the new service does not require any update through the App Store; rather, you can make a call by simply tapping on the name of the person you want to call from your conversation list, then select the "i" button on the top-right corner, and then tap Free call. The user, whom you want to make a call to, should also be using the Messenger for iOS app.

The "free voice call" roll out is a major milestone for Facebook as with this single feature, Facebook becomes one of the largest communities of VoIP users in the world, the report said. Testing the new service, The Verge said the call quality is as good as its competitors such as Skype, Vonage, and Viber.

"We started testing this in Canada the first week of the year and today we're extending that test to the U.S.," Facebook confirmed the news in an e-mail sent to Bloomberg Business Week. "We were able to expand the test so quickly because it went well in Canada and we wanted to expand the audience."

As the new feature arrives to iPhones, the U.S. users of the Apple flagship products can make free calls to other users via Wi-Fi or wireless network when they are on the go.

As Forbes' Robert Hof rightly notes, the new service will mark a change in the way people use Facebook because, with the recently launched Graph Search service and the new Free Voice Call, the social media Web site becomes more useful and informative than just entertaining.

A wide release of the free voice call feature (to Android and Windows phone users) will keep its 1 billion-plus user-base wedded to the service. In addition, the service will prove a strong attraction to the large pool of young users who often have limited voice or data plans.

Facebook is reportedly accelerating its efforts to bring this service to other mobile platforms and with the fact that nearly 60 percent of its members used mobile devices to access the Web site at the end of the third quarter, the potential reach of the service is quite large. Finally and most importantly, the free voice call service, which is all about better communication, can add value to what Facebook is all about - being social.

Facebook, however, did not elaborate on the international rollout of the service; neither did it offer more details on the VoIP calling through its Messenger app for Android or VoIP calling through the Web site.