Multichannel queueing system with refusals of servers groups

The multichannel queueing system SM/PH/n/r with unreliable servers and their group refusals is under consideration. The refusals and the restorations of servers groups occur with a constant intensity, the number of servers refusing simultaneously is a stochastic value, and customers with the interrupted servicing begin its servicing anew after server restoration. The methods are offered to calculate the stationary distribution of the number of the customers in the system under different variants of the functioning of the system.