It’s not polite to call someone out of the blue anymore. Best to text them first. That’s why Facebook thinks video calling will live naturally inside Messenger. Today, Messenger is launching free VOIP video calling over cellular and wifi connections on iOS and Android in the U.S., Canada, UK, and 15 other countries.

Facebook’s goal is to connect people face to face no matter where they are or what mobile connection they have. With Messenger, someone on a new iPhone with strong LTE in San Francisco could video chat with someone on a low-end Android with a few bars of 3G in Nigeria.

Here’s a quick video from Facebook showing Messenger video calls in action:

Facebook first introduced desktop video calling in partnership with Skype in 2011, but eventually built its own video call infrastructure. Bringing it to mobile could Messenger a serious competitor to iOS-only FaceTime, clunky Skype, and less-ubiquitous Google Hangouts.

With 600 million Messenger users and 1.44 billion on Facebook, the new VOIP video feature has a massive built-in audience. Mark Zuckerberg said on last week’s Facebook earnings call that Messenger already accounts for 10% of global mobile VOIP calls. He believes free, high audio quality VOIP will displace traditional phone calling, and video calling could accelerate that.