A method, and a related system, for estimating coverage of a selected geographic area by a cellular radio mobile communications network including a plurality of radio base stations, includes: dividing the selected area into a plurality of area elements and determining expected serving radio base stations expected to serve the area elements based on an estimation of the strength of the radio electromagnetic field of the radio base stations in the area element. The expected serving radio stations are determined by: estimating probabilistic distributions of the strength of the radio electromagnetic fields irradiated by the radio base stations and perceived in the area element; and calculating probabilities that the area elements are served by the radio base stations based on said probabilistic distributions. The method can be exploited in the planning of a network, for example, in the estimation of the distribution of traffic.