For a voice interaction, supervisors can monitor the incoming calls routed to agents or the outgoing calls initiated by agents. Supervisors can observe one active voice call at a time. Supervisors can listen to the real-time voice conversation between the agent and the customer. If the agent puts the call on hold that the supervisor observes and initiates a consult call, the supervisor starts observing the consulted call automatically for that agent. If the agent transfers the call that the supervisor observes, the supervisor is removed from that call and cannot actively observe the transferred call.