After previously allowing for audio messages to be sent from one Facebook Messenger user to the other, the company has now flipped the switch on free calling. However, this option is only available at the moment if you cumulatively 1. have an iPhone and 2. live in the U.S.
The program was tested in Canada and is now rolling out in the U.S., functioning on both WiFi and/or via a data connection. This is particularly useful if you live in a poor-coverage are or you want to reduce your monthly bill. By enabling voice calls (even though limited regionally), Facebook takes on Skype in the fight to become the largest VoIP service provider. You can grab the latest version of Messenger in the iTunes App Store.