A basis for transmission performance objectives in a telephone communication system

In any extensive telephone system, certain objectives and controls must be set up to provide and maintain satisfactory performance. This control of quality is as important in communication service as in manufacturing. Rather than stemming from an engineer's dream or a mathematical formula, quality is essentially a user's impression of the product. There is danger, therefore, in measuring it in terms of somewhat arbitrary physical limits. There is danger, too, in not recognizing what lies behind the objectives and the effects on the user when these are not met.