Facebook Messenger has launched free VOIP video calling over cellular and wi-fi connections on iOS and Android platforms.

The services will be available in the US, Canada, England and 15 other countries, TechCrunch reported. With 600 million Messenger users and 1.44 billion on Facebook, the new VOIP video feature has a massive built-in audience.

Messenger already accounts for 10 percent of global mobile VOIP calls, according to Mark Zuckerberg, one of five co-founders of the social networking website Facebook.

He believes that free, high audio quality VOIP will displace traditional phone-calling and video calling could accelerate that.

Messenger won’t be charging for audio or video calling. If you have access, you’ll see the video camera icon in the top right corner when you’re having a Messenger chat with a friend, who can be called.

Tapping it starts a video call, which opens when the recipient accepts. Cameras start in selfie mode but you can toggle to the backside camera to show a friend what you’re doing.

Messenger will adjust the quality of the call according to your connection. It’s easy to switch to just VOIP audio, and Facebook will notify the users if the connection weakens to where video won’t work.

One smart thing Messenger allows is for one person to turn off their video feed to make the other person’s high quality. This way, if you’re sitting at home and a friend is on a mountain in Norway, you can give them the extra bandwidth because what matters is seeing their scenery, not them seeing your bedroom.

Video calling in Messenger will be available in Belgium, Canada, Croatia, Denmark, England, France, Greece, Ireland, Laos, Lithuania, Mexico, Nigeria, Norway, Oman, Poland, Portugal, the US and Uruguay. More regions will be added in the coming months.