Traffic Analysis of Delayed Delivery Services Considering the Correlation Between Circuit Switching and Message Switching

To improve the ratio of successful calls, a new switching system permitting callers to store messages when the called party is busy or does not answer can be constructed by adding a message storing function to the conventional circuit switching system. The mutual traffic influences exerted by this combination of circuit and message switching systems have not yet been clarified. This paper considers a two-stage loss system traffic model consisting of a circuit switching system that has a message switching system connected to it. The traffic characteristics of this model are analyzed using the nonindependent state transition probability, which depends upon the interacting states of the circuit and message switching system. A method of solving the state equations by determining the state transition probabilities of the message switching system from the state probabilities of the circuit switching system is proposed. Using this method, the mutual traffic influence of the circuit and message switching systems is evaluated.