The 81-a exchange trunk carrier system

The post war expansion pattern of the telephone industry has created a substantial demand for carrier equipment suitable for exchange trunk connections. There is an increasing demand for these office-to-office connections in extended area service (EAS). It has been the cost rather than technical feasibility that has discouraged extensive use of carrier equipment in the exchange plant. However, if a carrier system is available at a price competitive with cable cost, the demand will support the sort of manufacturing volume that is associated with mass production techniques. It has been the primary design target of the 81-A carrier system to prove-in economically at distances as short as 2 to 3 miles, and thus a substantial market potential is insured.