Increased failure to access and engage communications channels, increased dropped calls and general poor quality of service are some of the persistent problems encountered in cellular net-works. The effect of these on the level of customer satisfaction and consequently on the generated revenue have necessitated the research into developing techniques for improving the performance of telecommunications networks. This paper presents an overview of three important performance evaluation models for mobile telecommunications networks with emphasis on Grade of Service and the Poisson nature of traffic. The stochastic models used in the study are based on applied probability theorems that best describe the peculiar nature of user traffic. Equations from the models are derived for key performance indices, which can be used in future applications to de-sign cost-effective systems that balance the inherent capacity-quality trade-offs that are character-istic of such networks.