Ever since launching its totally redesigned Messenger app last November, the social networking giant Facebook’s been dragging its feet in terms of enabling VoIP calling for everyone.

For users in the United States, Canada and the United Kingdom, this useful feature has been part of the old Messenger app for quite some time now.

Today, Facebook issued a minor update to Messenger for iOS that seemingly enables free voice calling over Wi-Fi and low-cost calls over cellular for everyone.

The update is available in the App Store so grab it now and check out free calling in Facebook Messenger…

Release notes for Messenger 4.1 mention:

Free Calls: Talk as long as you want and stay in touch wherever you are. (Calls are free over Wi-Fi. Otherwise, standard data charges apply).

So how does this work?

It’s real simple.

Once you and your Facebook friends around the world have the new Messenger app installed on your iOS or Android devices, hit the phone icon in the upper right of your chat session to call the person over your iPhone’s Wi-Fi or cellular data.

If that person is off the grid and can’t be reached at the moment, you’ll see a warning message. The phone icon will be greyed out for contacts that are unavailable for VoIP so you don’t even have to try calling them.

When the icon turns blue, the person is reachable. You can see below I was able to reach my friend Wolfgang who lives in Yorkville, Illinois.

The person receiving you call will get standard iOS push notification to inform them of an incoming call. In-call options include Speaker, Mute and Hide. Check out below the calling screen in Facebook Messenger 4.1. The calling screen is reminiscent of Apple’s stock Phone app in iOS 7.0, prior to the visual changes in iOS 7.1.

Facebook recently acquired WhatsApp for $19 billion.

By summer, WhatsApp will enable free calls so it’ll be interesting seeing whether Messenger and WhatsApp will be interoperable in terms of VoIP calling.

Download Facebook Messenger 4.1 free in the App Store.

iOS 6.0 or later is required.