One pair for both digital and analog (sl) phones. Is this a hotel/motel? If there are two pairs going to the rooms, this would indicate that they have (or might have had) phones that had a separate data port. This was when people had modems in their laptops.ite with

Are the cabints white with a glass front door---looking like a micro wave oven? Then it may be an ML/EL.

Do they have a console? Do they have a VM ? Why do they want another system? Mitels are made to last many, many years.