Facebook just started to test a new feature in its Messenger application that lets users call each other for free anywhere they have a Wi-Fi or cellular data connection. For now it only works with Messenger for iOS, but could roll out to Android users, as well as worldwide, if everything goes well.

It is very simple to use the service. To begin a call with someone in Messenger, then press the “i” button in the top right hand corner of the screen. Next, press the “Free Call” button, placed in the middle of the screen. For this to work, both callers must have an up-to-date version of Facebook Messenger installed on their smartphones.

It won’t alert you the way it does when you have a normal call: Facebook calls just show up as a push notification. And now, you can only connect with a conversation partner who also has Messenger installed on their iPhone.

You are able to make free Skype, Vonage, or Viber calls over Wi-Fi and cellular data, but far more people use Facebook than any of those services. Facebook Messenger app has consistently hovered near the top of the Google Play Store and App Store.

To those users without full functionality yet, the application reminds you that free calling is unavailable, mentioning that “You don’t have permission to chat with this person”

The Facebook Messenger app is currently available for free in the Apple App Store.

Do you like this new feature from Facebook? Let us know what you think.