: This paper contains description of an knowledge discovery experiment performed in radio planning department of one of Polish celular telecom providers. The results of using various data mining methods for GSM cell tra c prediction are presented. The methods used include both standard and well established approaches such as decision trees and k-means clustering, and new methods invented for this experiment, such as regressionalclustering. Remarkson importance of discretization methods for quantitative data mining are presented, together with general discussion on data mining of technical (i.e. mostly numeric and automatically generated) data.