Facebook recently started testing out free voice calling with its Messenger app for Canadian users. And now the social network has expanded the feature to the U.S., allowing users to make unlimited calls to Facebook friends for free. 

The new Messenger feature is currently available for iPhone owners only. Just like the beta version released in Canada, users will be able to call friends on their cellular network or via Wi-Fi connection.  Unfortunately, it's undergoing a slow rollout and, according to 9to5mac, it isn't available for everyone yet.

To check if you are able to call friends via Messenger simply open up the app, tap "i" in the upper right corner of an active chat then a "free call" button will be displayed. The feature is a silent update and does not require a download from Apple's App Store.

[via 9to5Mac]