Physical and Transmission Characteristics of Customer Loop Plant

A recent Bell System customer loop survey was jointly conducted by AT&T and Bell Laboratories. Bell Labs developed the sampling plan and performed the data analysis while AT&T assumed responsibility for the sample selection, data collection, and all intermediate data processing prior to analysis. This paper presents the principal results of this Bell System customer loop survey. This survey provides a statistical characterization of both the physical composition and the calculated transmission characteristics of customer loop plant. Comparisons of data obtained from the survey and a similar survey made in 1964 are also presented. The characterization of the Bell System customer loop plant as defined by the 1964 loop survey was published in 1969 by P. A. Gresh. 1 The current Bell System survey consisted of a simple random sample of 1100 main stations selected from the population of all Bell System main stations. Lines serving official telephones, foreign exchanges, dial teletypewriter exchanges (TWX), and special services were, however, omitted from the survey, as it was felt their design would not be representative of customer loop plant. 35