Which are the three holding time types to telephone system?

The three holding time types in a telephone system are:

1. Queue Time: The duration a caller spends waiting in line before being connected to an agent.
2. Talk Time: The actual time the caller spends conversing with the agent.
3. After-Call Work (ACW) Time: The time taken by the agent to complete any necessary tasks related to the call after it has ended, such as documentation or follow-up actions.