I need to make sure that none of the lines coming into my PBX are allowing access over a modem for management. I have found a few that give me the modem squall (I manually dialed every single DID). How can I tell if the line is used for a fax vs embedded modem for management or whatever in the PBX?

By management, I mean eManager, but don't know if there is any other management protocols that might exist.