This is a feature my department used with a previous company to "coach" calls that agents make to give them feedback on how to improve their calls, and listen in for training purposes. It was very helpful when agents were dealing with difficult prospects, or were still in training and unsure of what to do. This way, supervisors could listen and become aware of what was going on in the call without interrupting and asking the agent.
I like to "coach" my agents to rate their performance and give them accurate and relevant feedback on how to make their calls more successful with various types of prospects. We can also watch for suspicious activity on the part of our agents. For example, if we suspect they are hanging up on prospects, using live call monitoring can help us prove if they are doing so. Only Staff would have this capability.