As soon as more orders are received than can be processed within a period, queues occur. This affects the company’s performance and represents a challenge that has to be dealt with. Hence, the understanding and management of queues is a fundamental task for the operations management. In summary, it can be said that the queueing theory provides only the possibility to support planning functions. However, a certain behaviour of the system has to be assumed by the adoption of certain distributions (exponential function). In reality, several simulations are necessary otherwise the results may not be meaningful because they could offer a high spread. In some cases, adjustments of the system may be necessary. All in all, the use of the queueing theory theoretically enables managers to calculate and simulate a queueing model in a short time.