Tandem queueing system with impatient customers as a model of call center with Interactive Voice Response

A tandem queueing system with a Markovian Arrival Process ( M A P ) useful in modeling a call center with Interactive Voice Response ( I V R ) is investigated. The first stage has a finite number of servers without buffer while the second stage of the tandem has a finite buffer and a finite number of servers. The service time at the first (second) stage has an exponential (phase type) distribution. A special approach for reducing the number of states of the stochastic process that describes the behavior of the system is used. The main performance measures are calculated. The Laplace–Stieltjes transform of the sojourn time distribution is derived. The numerical results are presented.