In this paper, we propose a new technique for the performance analysis of cellular mobile communication networks based on a frequency division multiple access/time division multiple access scheme (such as global system for mobile communications), in which the utilization of two separate frequency bands leads to a complex cellular structure with overlapping microcells and macrocells. Call durations and dwell times are described by random variables with general distributions; the call duration distribution is then approximated by a two-phase hyper-exponential distribution with the same first and second moments as the original general distribution. The analysis technique is based on Markovian assumptions as regards the traffic flows entering both microcells and macrocells, as well as an assumption of flow balance between handovers into and out of any cell. The analytical model is validated against results of detailed simulation experiments for various system configurations, and shown to provide quite accurate predictions.