It is known that efficient call handling mechanisms can greatly improve cellular network performance. However, modern cellular mobile network dimensioning is often based on rough estimates than on realistic analytical models for the applied protocols and expected traffic behavior. The application of more detailed traffic models shows, that actual load and probabilistic traffic properties considerably differ from those used for estimation. This can lead to inaccurate calculation of QoS parameters and network operator costs. In this paper we consider call handling schemes in cellular mobile networks based on complete sharing and guard channels for the case of blocked call retries. We present a simple analytical method for approximate calculation of blocking probabilities for this case. As a part of the method we derive the average number of failed repeated attempts per one blocked call which we consider to be an important parameter in cost calculation. © 2003, Institute of Electrical and Electronics Engineers Inc. All rights reserved.