A method of identifying areas for improving radio communications coverage in a mobile radio network under analysis. The method comprises detecting cancel location signalling data, update location signalling data and service signalling data. The cancel location signalling data is generated to cancel a registration of mobile user equipment from a visitor subscriber database of the analysed mobile radio network. The cancel location signalling data includes mobile subscriber identifiers of the mobile user equipment. The location update signalling data informs the home subscriber database of the home network of the mobile user equipment that the mobile user equipment is to be registered as having roamed to a visitor subscriber database of at least one other mobile network. The location update signalling data includes identifiers of the visitor subscriber database and the mobile subscriber identifier of the user equipment being registered. The service signalling data is associated with mobile originated calls made by mobile user equipment as part of service provisioning to the mobile radio network being analysed. The service signalling data includes mobile subscriber identifiers of the mobile user equipment and identifiers of cells of the analysed mobile radio network from which the mobile originated calls were made. The method includes correlating the cancel location signalling data and the update location signalling data with respect to the mobile subscriber identifiers of the mobile user equipment to identify mobile subscribers lost to the other mobile network. The method identifies areas of relative loss of service of the analysed mobile radio network by identifying, from the subscriber identity numbers, a number of the lost mobile subscribers which had made mobile originated calls from cells identified by the cell identifiers of the service signalling data.