A Study of the Delays Encountered by Toll Operators in Obtaining an Idle Trunk

A Study of the Delays Encountered by Toll Operators in Obtaining an Idle Trunk By S. C. R A P P L E Y E HE aim of the Bell System is to give the fastest possible toll service consistent with costs. The aim of the Intertoll Trunk Engineer is to provide the proper number of trunks in each group to obtain that objective. His problem is to gauge the effect of his work on the overall speed of service. Overall speed of toll service is the elapsed interval from the filing of a call until conversation starts or until there is a definite report about the called party. This overall speed includes the operating time or interval required for the operators to establish the connection; the subscriber time or interval required for the calling party to give the details of the call, for the called party to answer his telephone, etc.; and the circuit delay time or interval of waiting for a trunk to become idle. This last factor may be termed the trunk speed interval. The proportion of this trunk speed to the overall speed is an important factor in determining the number of trunks to be provided. If it is a large proportion of the total, a marked improvement may be expected as a result of providing more trunks. Conversely, if the trunk speed is a small proportion of the total, the improvement to be expected as a result of providing more trunks will be small also, with a diminishing rate of improvement until the trunk speed ceases to be a factor. The trunk speed in turn depends upon three factors: Group size--number of trunks to the called city or in the direction of the called city.