North, and Northcom were products produced for the distribution unit of the United Telephone System. This company was called North Supply, later becoming Sprint/North Supply, then Embarq Logistics and finally KPG Logistics. All of these systems came from the same manufacturers, with the majority being Lucky Goldstar, later LG Electronics. They made systems marketed under many, many different name brands. The documentation similarities are because they were printed by the same source and just altered with the different brands' logos.

They didn't make systems for Inter-Tel or Mitel though.

Ed Vaughn, MBSWWYPBX