Artalejo Rodríguez, Jesús ManuelMartin, M.2023-06-202023-06-201995-09-030001-867810.2307/1428136https://hdl.handle.net/20.500.14352/57500The authors would like to thank the referee for valuable suggestions that helped to improve the presentation of this paper.This paper deals with a service system in which the processor must serve two types of impatient units. In the case of blocking, the first type units leave the system whereas the second type units enter a pool and wait to be processed later. We develop an exhaustive analysis of the system including embedded Markov chain, fundamental period and various classical stationary probability distributions. More specificp erformancem easures,s uch as the numbero f lost customersa nd other quantities,a re also considered.T he mathematicaal nalysiso f the model is based on the theory of Markov renewal processes, in Markov chains of M/G/1 type and in expressions of 'Takacs' equation' type.engjournal articlehttp://www.jstor.org/stable/1428136?origin=JSTOR-pdf&http://www.jstor.org/restricted access519.8Queues with impatient units and repeated attemptsTakacs equationMatrices of M/G/1 typeMarkov renewal processesInvestigación operativa (Matemáticas)1207 Investigación Operativa