Facebook enables no cost iPhone voice calls.

Facebook's app transmits calls in your phone's broadband connection, whatever it's -- 3G, 4G as well as Wi-Fi. Instead of sucking up your monthly allotted voice minutes from the cellular carrier, it sucks up megabytes from the data plan. That's any boon for heavy talkers with unlimited data plans.

It is nothing new or computer groundbreaking: Skype was executing it long before Facebook. Facebook has many more active users than Skype, even though, and the allure of needing to use one fewer network or app will fascinate some (perhaps many).

But it isn't all roses just yet. For now, this is usually a pretty limited offering.

Your phone won't alert you the way in which it does if you have a normal call: Facebook calls just make an appearance as a push notice. And right now, you'll be able to only connect with any conversation partner who has Messenger installed on their particular iPhone.

There's no strategy to ring up a Facebook friend that is logged in through it, and there isn't by any means to place a call to some ten-digit phone number. Calling remains to be absent from the Android os and BlackBerry versions from the Messenger app.

There's a good reason for those omissions. The VoIP features within the Web version of Facebook or myspace were built using Skype's systems, while the calling technology in Messenger is almost all Facebook. The ability to place and receive calls using traditional telephone numbers requires telecommunications resources Facebook has not got (at the moment, on least).

For the time being, services such as Yahoo and google (GOOG, Fortune 500) Voice and Skype have a leg up, given their particular larger feature sets. But Facebook generally doesn't let anything be in stasis for long. As we've seen before -- and caught any glimpse of yesterday with the Graph Search reveal -- Facebook likes to start small, and continuously flesh out its goods. Expect the same with voice calling.

And not like Google Voice and Skype (which is actually owned by Microsoft (MSFT, Bundle 500)), Facebook is 100% system neutral. Facebook (FB) doesn't care if you are using its app on a iPhone, Android, Windows Phone, BlackBerry or something nuts like Ubuntu.

In a period when every company is saving the very best features of its products for its own mobile ecosystem, Facebook has the opportunity to both usurp the direct competition and build out a telecom-slaying words service.