Artalejo Rodríguez, Jesús Manuel2023-06-202023-06-201995-050167-637710.1016/0167-6377(95)00017-Ehttps://hdl.handle.net/20.500.14352/57502The author would like to thank the anonymous referee for his comments which helped to improve the quality and clarity of the paper. This work was supported in part by the University Complutense of Madrid under grant PR161/93-4777.We consider a queueing system where a customer who finds all channels busy must decide either to join the queue or to retry after an exponentially distributed time. The performance of the system can be approximated by using the RTA approximation introduced by Wolff and Greenberg. We present numerical results demonstrating the performance of the approximation for various representative cases.engjournal articlehttp://www.sciencedirect.com/science/article/pii/016763779500017Ehttp://www.sciencedirect.com/restricted access519.8Retrial queuesRTA approximationSimulationInvestigación operativa (Matemáticas)1207 Investigación Operativa