Last week when Facebook updated its Facebook Messenger app for the iPhone it included free voice calling in the U.S. A users can place a call to contacts from the conversation list if that person has Messenger for iOS meaning both parties need to be using the Messenger app.

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The APK also revealed that there's a host of circular Facebook-flavored icons and tight Facebook Messenger integration.

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Previously Facebook Messenger was an app for Facebook users to communicate with other Facebook users through instant chat.

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