The present invention relates to a method and apparatus for forcing a mobile device to handover from a first cellular network radio access technology (RAT) to a second radio access technology (RAT) different from the first cellular network radio access technology. The method comprises: establishing a connection with the mobile device using the first cellular network radio access technology; sending a handover command to the device using the first cellular network radio access technology, the handover command including details of radio resources of the second cellular network radio access technology; and establishing a connection with the mobile device using the radio resources of the second cellular network radio access technology which were specified in the handover command. These steps are each performed by a separately introduced base station which is not under the control of a cellular network.