Facebook has just announced that it now allows group voice calls to everyone through Facebook Messenger. As you can see, the new feature will be available to all social network users during the next 24 hours. 
So if you do not have it yet, make sure you have the latest app update.
For those who already have this feature in Messenger, tap the phone icon to start a group chat call. The next screen will allow you to select the people you want and invite them to your chat.
Of course you won't be able to chat with many at first as everyone will have to install the latest version of the application.
Also currently the app doesn't support video chats, but it probably will theme time before Facebook activates them with a subsequent update.
Facebook has not yet reported how many can take part in group voice calls.
