Listen, Whisper, Barge
These are powerful advanced call center features allowing supervisors to listen in on agent conversations while being able to speak to the agent only or agent and customer for quality control, training and escalations.
Listen. A supervisor can silently monitor a two-party call made by or answered by an agent on a conversation with an external party. No audible sound would alert the agent or the customer that the conversation is being monitored.
Whisper. A supervisor silently monitoring a call between an agent and a customer can privately speak to the agent, without the customer hearing the discussion. When the whisper feature is activated, the supervisor can begin speaking to the agent. This is one-directional audio from supervisor to agent. The customer will not hear the whisper. Both supervisor and agent can hear the customer.
Barge. A supervisor who is silently monitoring a call decides to enter the conference bridge, joining what then becomes a full three-way conference call, where all three parties can hear each other.