This work studies the improvement in service coverage obtained by three different approaches to combining two triangulation (terrestrial and satellite) location methods for cellular networks in an urban environment. The paper assumes that the terrestrial cellular network uses enhanced observed time difference (E-OTD) in 2G or observed time difference of arrival (OTDOA) in 3G, while the satellite GNSS uses the assisted global positioning system (A-GPS), but the analysis can be easily generalised to other triangulation methods. A straightforward analytical model is presented to evaluate the service coverage resulting from each of the three approaches. The model is fed with actual coverage figures, gathered from test measurements carried out in Paris (France) for several urban scenarios. Numerical results show that the three approaches lead to improvements in all the tested scenarios, and that the improvement obtained by the increasing complexity of the fusion approach depends highly on the coverage of each individual method and on the joint probability function of individual performances