An analysis of the probable impact on communication systems of LSI (Large-Scale Integration), a new technology that enables placing the equivalent of hundreds of transistors on a single silicon pinhead. Included are a review of the communication system components subject to LSI, a consideration of those system elements not economically achieved with LSI, and comments on desired major changes in direction in communication systems. LSI is most applicable where (1) very many identical units of complex circuitry are needed, (2) a small number of input, output, and power leads are required, (3) digital signals are processed, and (4) power consumption is low. Although the analog signals used in today's communications networks are generally incompatible with LSI, even such highly analog functions as frequency filters can be provided by the use of all-digital circuitry. LSI digital filters can have better properties, lower cost and smaller size than their analog counterparts. LSI is not superior to discrete elements when large powers must be dissipated, however.