Call Monitoring at Multiple Levels

[underthebus]

I have a customer that has 5 levels of management. He wishes to have the manager in the lowest level of management (level 5) to monitor calls at level 5. the manager at level 4 should be able to monitor calls at level 4 and 5. The manager at level 3 should be able to monitor calls at level 3, 4, and 5. Basically, the lower levels of management should not be able to monitor calls of those in the higher level.Is this possible? If so, how is it achieved? what licenses are required?

Thanks in advance.