Delay curves for calls served at random

This paper presents curves and tables for the probability of delay of calls served by a simple trunk group with assignment of delayed calls to the trunks at random and with pure chance call input. These are contrasted with the classic results of Erlang (“Erlang C”) which are based on service in order of arrival. Trunk holding times for both have an exponential distribution. The theoretical development for computation of the curves is directed to the determination of the moments, which seem to be a natural means of simplification.