In this paper, we have investigated the waiting time/delay of a broad class of mobile communication system-oriented queuing models. Both exact analytic and approximation algorithm techniques are employed in order to obtain the exact and approximate waiting/delay distribution of those models. We concentrate on probability distribution instead of mean value because a one-point estimate is not sufficient to provide a good performance evaluation. We propose different queuing models in order to describe different characteristics of mobile systems. Different server control mechanisms are implemented in order to optimize channel (or server) utilization. Here the tandem queues with BAS blocking policy are investigated.