“…Main fields where such models are used are telecommunication networks, computer networks, call centers, wireless communication systems, cognitive networks, cloud computing. An extensive review of recent developments and methods related to RQ systems one can find in, for example, Artalejo, Falin [2], Artalejo, Gomez-Corral [3], Gomez-Corral, Phung-Duc [16], Falin, Templeton [13], Kim, Kim [17], Nobel [24], Phung-Duc [26].…”