Disclosed is a method of identifying interference in a cellular telecommunications network including a plurality of cells controlled by a base stations 5, each cell serving a plurality of mobile devices 1 by radio link by using communication resources allocated to each of the mobile devices, the network having a frequency band allocated thereto. The method includes detecting radio quality within the frequency band at at least one of the cells to produce measurement values; and analyzing selected ones of the measurement values to determine if the selected measurement values indicate the presence of interference, wherein the selected measurement values exclude the measurement values relating to the communication resources allocated to each of the mobile devices served by the cell.