Facebook Messenger now offers free calling, as the feature has made its way to US iPhone users. The standalone Facebook app allows users to open a conversation with another Messenger user by opening a conversation, tapping the “i” button, and then tapping the new Free Call button. The calls are free using Wi-Fi or the iPhone’s data connection. The VoIP calling service was announced as a new feature about two weeks ago. An App Store update is not needed to start making calls.