On this page
Start a 1:1 Call
-
Go to your chat list, and click New chat
to start a new conversation. -
Type the name or names into the To field at the top of your new chat.
-
Select Video call
or Audio call 
to start a call.
Up to 20 people can be on the same video call.
Accept Incoming Calls
-
Select an incoming call with video turned on or just audio. You can also decline the call.
Video Tutorial
Watch this brief tutorial on how to start a call from a chat: