On the multiserver retrial queues with negative arrivals

The paper deals with an M/M/C/K retrial queue with exponential abandonment at which positive and negative customers arrive according to Poisson processes. This model is of practical interest: it can be used for analysing the performance in call centres and e-mail contact systems. For the model under investigation, we find the ergodicity conditions and also the approximate solution by using finite truncation and value extrapolation methods. We present some numerical results to examine the performance of the value extrapolation method as well as the system performance.