Home › Authors › Yankee Group. Communications Systems and Services 👤 Yankee Group. Communications Systems and Services 5 books Books by Yankee Group. Communications Systems and Services Alternative access carriers Alternative access carriers 1990 Customer, carrier, and competi Customer, carrier, and competitor 1990 Future tariffs Future tariffs 1989 Voice processing alternatives Voice processing alternatives 1987 Voice systems network manageme Voice systems network management 1987