Simple-closed expressions for approximate calculation of quality of service (QoS) metrics of isolated cell of wireless networks with either finite or infinite queues of both new and handover calls are developed. It is assumed that both kinds of calls might leave the system without receiving service if their waiting times exceed some threshold value. For the models with infinite queues of heterogeneous calls easily checkable ergodicity conditions are proposed. The high accuracy of the developed approximation formulas is shown. Results of numerical experiments are given.