The ability to describe experimentally obtained delay values in a cell of a mobile cellular network allows not only describing the properties of cell delays using only a few parameters, but also to simulate delay values. Unfortunately, occasionally occurring temporary unstable operation of a cellular network, caused by various negative factors, leads to a noticeable increase in delays and, as a result, to a significant distortion of the obtained delay parameters estimates. For this reason, estimates of the delay parameters in a cell should be obtained from experimental data obtained at the time of stable operation of the network. Due to the large amount of experimentally obtained data, the process of checking experimentally obtained delay values for the presence of anomalies should be performed on the application of simple criteria. The aim of this paper is to show an approach to obtaining stable parameter estimates of delay in a cell of a mobile cellular network. The article describes the factors that affect delays stability, assesses the degree of their influence, and also highlights properties that can be used to recognize phenomena that adversely affect the value and stability of delays in order to exclude such experimentally obtained data from the evaluation.