Facebook gives you the ability to get in touch with your other Facebook buddies through voice and video calls.
How To Make Facebook Video/Voice Calls
You won't need to download and install any third-party browser plugins or programs. Sign in to your Facebook account using your favorite web browser (Google Chrome, Firefox, Opera, or Safari), open a chat with the desired contact, and click on the Phone/Camera button to begin a call:
How To Turn Off Facebook Video/Voice Calls
If you don't want to be disturbed by unsolicited calls when you connect to Facebook, you can permanently turn off this feature in the chat settings. Open the Chat window, click on the cog icon (Options), and then select Turn Off Video/Voice Calls: