Earlier this month, Facebook (NASDAQ:FB) began testing the ability to call from one iPhone to another using the company's Messenger for iPhone app in Canada. Now, Facebook is rolling this feature out to the United States.
Using the Messenger for iPhone app, you should now be able to make a call to another Messenger for iPhone user. According to Facebook, you shouldn't need to update through the App Store to get this functionality which works over Wi-Fi as well as 3G and 4G cellular networks. Of course, you'll want to be careful of using the feature over cellular networks unless you have an unlimited data plan. To call a friend using Messenger for iPhone simply open a conversation with that person, tap the "i" button, and then select Free Call.
With the addition of this feature, Facebook emerges as one of the largest communities of VoIP users around the world. If you live or work in an area with poor cell service or if you have a cell phone plan with limited minutes, this feature should be especially useful when used with a Wi-Fi network.
Facebook hasn't announced any plans to offer the same functionality through its Messenger for Android app or through its website, but we're assuming these features are coming at some point in the future.