Facebook has added a feature in its mobile phone app that allows free calling for US iPhone users.

Users can now make calls to each other via the Facebook Messenger app anywhere they have a wi-fi or a cellular-data connection.

The feature could be a boon for heavy talkers as they would avoid carrier call charges.

Facebook said it was working on adding the feature to its Messenger app for Android and BlackBerry users. Facebook Adds Free Calls For U.S. iPhone Users [bbc.co.uk]