Facebook has officially launched VoIP call functionality for its iOS Messenger app in the US, which it started testing just two weeks ago.
The function enables users to call their contacts in-app, across a data connection, as part of their IM conversation. The recipient will then see a push message telling them they're being called.
With Facebook's huge userbase - somewhere in excess of 1bn globally - rolling out this feature could essentially make it the world's largest VoIP provider overnight. It also represents another obstacle for operators' traditional revenue sources, putting an increased emphasis on data.