What do you use to send instant messages, maintain your calendar, take and share photos, check your email inbox, leave voice messages, look up restaurants nearby, and store your contacts when you’re away from your desktop computer?
The big answer is: your smartphone, of course. But more specifically, you might actually be using the Facebook apps you’ve loaded on that phone.
Over the last couple of years, Facebook has packed its mobile apps with much of the same functionality as operating systems like Google’s Android, Apple’s iOS, or Amazon’s version of Android for Kindle Fire. It has not, however, launched the Facebook phone  that once seemed inevitable.
That's because your phone already is a Facebook phone. Android, Apple, whatever--with a strategy to make Facebook tools the go-to apps for everyday mobile living, the device type doesn't matter.
“People keep asking if we’re going to build a phone--and we’re not going to build a phone,” Zuckerberg insisted for perhaps the millionth time during Wednesday’s earning call. “It isn’t the right strategy for us to build one integrated system where--so let’s say we sold 10 million units, that would be one percent of our users--who cares for us?"
According to Comscore , Facebook already owns 23% of time spent in apps on Android and iOS. It also owns Instagram, one of the apps with which mobile users spend the second most amount of time (it's tied with Gmail and YouTube at 3%). The more time the company controls on its competitors' phones, the less important it is that it doesn't have its own devices. “We’re going to keep on pushing to get more integrated with the systems," Zuckerberg continued Wednesday. "Rather than building an app that is a version of the functionality you have today, making it so you can go deeper and deeper, I think, is going to be a big focus for us.”
A flood of new features that accomplish basic mobile tasks could help the company control more of the time--even most of the time--spent with any phone. Last year, for instance, Facebook updated its events to work more like a calendar  (though not on mobile yet). It launched a separate text-message-like messenger app  in August 2011, and added free voice calling  to it this January. Facebook acquired the dominant mobile camera across all systems with Instagram. Then it launched its own app store .
That's not to say that most people do, or ever will, use all of the operating system-type functionality Facebook provides. But imagine the potential combined power of all these small features: If you're using Facebook messenger instead of texts, messages instead of email, events instead of a calendar app, voice messaging instead of a phone call, Instagram instead of your camera app, searching for nearby restaurants using Graph Search  instead of a native maps app and discovering additional mobile experiences in the Facebook app store, does Android or iOS really own your experience on your mobile device?
No, you're essentially using the Facebook operating system--it's just packed inside a handful of apps.
Already Facebook has 680 million mobile users, more than either Android  or iOS . Google and Apple have made it pretty easy for the company to wheel its Trojan horse into their devices. An integration with iOS 6 syncs calendar appointments and contacts and allows posting to Facebook from outside the app. Android is such an open environment so, as Zuckerberg put it on Wednesday, "Even though our relationship with Google isn’t one where the companies really talk, we are able to do a bunch of things that they have an open platform that lets us get deep into the platform."
Instead of competing with other device makers and operating systems, Facebook has based its strategy on infiltrating the entire mobile experience from inside its apps. Apple and Google might still control the buttons, the app downloads, and the swiping signals, but Facebook is on the way to controlling what it cares about--their users' time.
[Image: Flickr user Felix Schmidt ]