Abstract. We propose a method of studying M / E _S / 2 / m, M / E _S / 2 / ∞ queueing systems including the case of random dropping of customers. Recurrence relations are obtained for computing the stationary distribution of the number of customers in a system and its steady-state characteristics. The developed algorithms are tested on examples using simulation models constructed with the help of the GPSS World tools.

Keywords: two-channel queueing systems, Erlangian service times, random dropping of customers, fictitious phase method, recurrence relations, steady-state characteristics.