The Evolution of Wideband Services in the

The growth of the telephone network in the United States since the 1920's has been rapid and continuous. This ex- pansion has been achieved largely through the application of carrier techniques. Most of the carrier systems, in addition to providing a number of voice bandwidth circuits, also have the capability of providing circuits of wider bandwidths. Through the years there has been a steady increase in the number and variety of communica- tion services that require these wider bandwidths. These wide- band services, as they are generally called, include telemetry, data, and graphic systems. Their evolution is traced and their technical requirements are briefly discussed.