No. 4 ESS: Performance Objectives and Service Experience

Abstract

The development plan of the No. 4 ESS included provisions for measuring the effectiveness of the design, operation, maintenance, and administration of the total system. This paper reviews system performance from 1976 to 1980, describes principal factors affecting system performance, and presents the service experience measured for the No. 4 ESS. Steady improvement has been measured in the number of service‐affecting incidents experienced per office each month. This improvement is also reflected in the rate of cutoff and denied calls, as well as in system “no call processing” time. We discuss some of the factors influencing this performance record, e.g., a sound initial design, reliable hardware, effective maintenance and repair tools, continuing analysis and resolution of causes of service‐affecting incidents, and continuing development of new features for performance improvement.