Application of queueing models with abandonment for Call Center congestion analysis

Abstract This paper studies and applies queueing systems to Call Centers regarding the possibility of customer abandonment from the system before being served due to their impatience in waiting for a service. Call Centers are service organizations that predominantly serve customers via phone calls. One of the main concerns in managing them is to provide quality service at a minimum cost. Noticing the quality of services offered is expressed by customers, for example by abandonment from the queue. This paper shows that the M/M/c+G analytical queueing models with abandonment, with patience time represented by generic distributions (particularly mixed distributions), are more effective than the M/M/c+M analytical queueing models with abandonment, with Exponential patience, commonly used to evaluate congestion problems in Call Centers and support sizing and operational decisions in these systems. We conducted a study using data extracted from a Bank Call Center located in Israel and the parameters and some performance measures are determined based on this data. These sampling measures are compared with the same measures achieved by the M/M/c+M and M/M/c+G analytical queueing models considered in this research, which use parameters obtained empirically and the mixed and non-mixed distributions based on Exponential and Lognormal to represent user patience. An experimental discrete simulation model was also used to explore an alternative scenario, showing the potential of using the approaches based on analytical models with abandonment for Call Center analysis. Resumo Este artigo estuda e aplica sistemas de filas para Call Centers considerando a possibilidade de o cliente abandonar o sistema antes de ser servido, devido a sua impaciência na espera do atendimento. Os Call Centers são organizações de serviço que predominantemente servem os clientes via chamada telefônica e uma das principais preocupações nas suas gestões é oferecer serviço de qualidade com mínimo custo. A percepção da qualidade dos serviços oferecidos é manifestada pelo cliente, por exemplo, por meio do abandono da fila de espera. Neste trabalho mostra-se que modelos analíticos de fila com abandono M/M/c+G, com tempo de paciência representado por distribuições genéricas (particularmente distribuições mistas), são mais efetivos do que os modelos analíticos de fila com abandono M/M/c+M, com paciência Exponencial, comumente empregados para avaliar o problema de congestão em Call Centers e apoiar decis