The barge feature gives the Supervisor the option to join an active call. When joining, a conference call will be created between the supervisor, the agent, and the person on the line.
In order to Barge into a call, you need to be an admin and then access the Call Monitoring tab area by going to your Admin Dashboard and see Live Calls:
From here you can use the Feature by clicking the Barge button near the call that you want to Barge to.
To stop and exit the call simply click the red Exit button