It seems that Facebook's test in Canada of free voice calls for iOS users has been a success, with the company now tipped to roll the feature out in the US.
Earlier this month, Facebook started offering Canadian users of its Messenger app the ability to make voice over IP (VoIP) calls to other Messenger users. Placing a call simply involves tapping the 'i' button on the top right hand corner of the screen and hitting 'free call'.
While FaceTime gives a similar ability, and with video to boot, it doesn't work on older iPhones.
Now, Facebook's introducing the feature across the US, saying it plans to roll it out over the next few weeks. Calls can be made over Wifi or a phone's data connection - although in this latter case, calls may not actually be free, depending on the user's data plan.
These days, very few people use their phone enough for calls to use up their monthly allowance. Those that do, though, are often exactly the same young and impecunious types that have become Facebook's natural market - although perhaps not Apple's.
Facebook's enormous customer base - over a billion, and counting - could potentially make it the biggest VoIP company in the world, outstripping even Skype - with which the company has a presumably now-redundant partnership.
And from the company's point of view, the service could offer all the advantages of the much-rumored-but-never-materializing Facebook phone, by encouraging users to spend that much more time on the site.
Facebook Messenger is available free from the Apple App Store.