Facebook is rolling out voice calling for groups in its Messenger app. In adding yet another smartphone function to Facebook's domain, the company is taking another step towards total mobile domination.

For a while, Facebook's strategy on mobile has been pretty obvious: Provide every service a smartphone user could need within Facebook or its cousin apps, so users never have to leave the platform.

Want to watch videos? Forget YouTube. These days Facebook's native videos are aggressively vying to become users' default option.

Want to message someone? No need for texting or Hangouts. You'd probably use Messenger, since nearly everyone you know is on Facebook. Or you could use Facebook subsidiary WhatsApp, now featuring end-to-end encryption.

But surely, when it comes to actually calling people, your phone is still... a phone right?

Group Calling on Messenger

Soon you may be rethinking that. On Wednesday, Facebook announced its plan to make your phone a full-on Facebook affair with the imminent global rollout of group Internet audio calls (VoIP), coming to the Facebook Messenger app.

The Messenger app update is simultaneously available on Android and iOS (for free). You'll know it's happened when you see a phone icon next to your contacts' names.

Click on that icon and a very familiar thing will happen -- you'll call them. Except you won't be using your mobile device's native phone "feature" (need I remind you that used to be the only thing cellphones did?), you'll be voice chatting within Facebook's platform.

Cue the panic alarms for wireless carriers worried about customers going for data-only alternatives.

The voice calling update to Messenger isn't just about needlessly replicating the core function that every smartphone has. It offers one major feature that may entice users to give up the old way: Quick, easy, and massively capable group calling.

Features and Advantages

As TechCrunch detailed, unlike the awkward, limited, and sometimes expensive conference call of old, on Messenger up to 50 people can participate in a group voice chat.

Whether anyone could feasibly conduct a sane conversation at Messenger's max capacity is another question. (There is a mute button.)

There are other advantages to Messenger's voice calling feature, which for one-on-one conversations rolled out last year.

First off, Messenger allows you chat with people whether or not they're friends with you, making Facebook's massive user base into something of a universal, global phone book.

For the privacy conscious, using Messenger gives you the freedom to reserve your actual phone number for those special few people -- like only the people you'd be okay with calling you up in the middle of the night.

On top of that, Messenger allows you to block people with a touch of a button, which for old-fashioned wireless telephony still sometimes requires users to get in touch with their carriers' customer service department. Facebook's anti-spam systems also help act like its own do not call list, weeding out further unwanted harassment.

The next step is probably video calling, but judging by Facebook Messenger's metrics, the takeover of your smartphone is already well underway. Since rolling out individual voice calls around this time last year, Messenger has already grabbed a 10 percent share of all global mobile VoIP traffic.