Overload model of telephone network operation

An analytic model for the steady-state behavior of an overloaded telephone network is given. The model includes trunk and machine congestion, retrials, “don't answer and busy,” and some network management controls. It is significantly cheaper to use than Monte Carlo simulations for moderate size networks. It compares well with Monte Carlo simulation calculations of point-to-point completion probabilities and the expected number of messages in progress. It compares less well for sender attachment delay and probability of time-out calculations in switching machines.