Facebook video call button is not in message window or in person's profile. Why and how can I fix it?

[Lizeth Gutierrez]

I'm trying to video call my cousin using the Facebook call button, but one isn't present and isn't being shown on either the chat window or my cousin's profile. I have already installed an internet connection (Firefox) that supports the video calling, but the button is still not available to click. I really want to be able to contact my cousin using Facebook because I can't install Skype and neither can she. Please and thank you!

[Md]

Before you can call friends from Facebook, you need to complete a quick, one-time setup. You'll be asked to complete the setup the first time you try to call a friend, or the first time a friend tries to call you.

To call a friend:

Go to their timeline and click Call at the top.
Click Set Up and follow the instructions for your browser.
Once you’ve successfully completed the setup, the call you’ve started with your friend should connect automatically. If it doesn’t, you can call again.
Learn more about how to make a video call and talk to your friends face to face.