I am using EDHU because he wants to use his cell to monitor if possible, he doesn't have a Mitel handset at all. I enabled the monitor option in the EDHU COS to test and it doesn't seem to work. I looked for a feature matrix (not very hard) and couldn't find one to reference. I will look harder when I get a chance.
You don't have to be an ACD agent or supervisor to monitor or to be monitored.