To start a Facebook video call
Open a chat window.
Click the camera icon in the top right corner.
If I’m not currently able to receive a video call the camera icon will be grayed out, and you’ll see a message that says “Lisa is currently unavailable for video calling.”
Having trouble? Make sure you’re using a supported browser, and that your camera and microphone are set up correctly. For more help, go to Getting Started | Facebook Help Center.