Before revision: The Mitel Superset Series of Office Telephones The Mitel Superset 4DN Telephone The Superset 4DN was one of the first Digital Telephones made by Mitel Mitel SUPERSET 4DN Mitel Superset 400 Series The 400 range consisted of a 401+,410,420 and 430 The telephones connected back to the Mitel exchange digitally using 1 pair of cables.
After revision: SeeThe Mitel Superset Series of Office Telephones The Mitel Superset 4DN Telephone The Superset 4DN was one of the first Digital Telephones made by Mitel Mitel SUPERSET 4DN Mitel Superset 400 Series The 400 range consisted of a 401+,410,420 and 430 The telephones connected back to the Mitel exchange digitally using 1 pair of cables.