A method of performing device handover in a wireless access network having a plurality of wireless access points for providing connectivity to a plurality of mobile devices wherein each mobile device is operable to connect to different ones of the wireless access points in dependence on their location within the wireless access network, the wireless access points being connected to a management server for exchange of control data between sets of wireless access points in relation to the mobile devices, the method comprising: a first wireless access point having a connected mobile device: monitoring for probe requests issued by the connected mobile device, indicative that the mobile device is seeking to handover to another of the plurality of wireless access points; determining the signal strength of a wireless link between said first wireless access point and the mobile device; sending a message to said management server, the message containing the determined signal strength and an identifier for the connected mobile device, the management server: receiving the message from the first wireless access point; storing the identifier for the mobile device and the determined signal strength in a data store, wherein the determined signal strength is stored as a threshold signal strength for handover for that mobile device, at least one second wireless access point: receiving a probe request from said mobile device; sending a second message to the management server, including details of the probe request, an identifier for the mobile device and an observed signal strength, wherein the management server further performs the steps of: receiving the second message from the at least one second wireless access point; retrieving the threshold signal strength associated with the mobile device from the data store; determining whether the observed signal strength between the at least one second wireless access point and the mobile device is above the stored threshold signal strength associated with said mobile device; if the observed signal strength is above the threshold signal strength, then instructing the second wireless access point to respond to the probe request, if the observed signal strength is below the threshold signal strength, then instructing the second wireless access point to ignore the probe request. a first wireless access point having a connected mobile device: monitoring for probe requests issued by the connected mobile device, indicative that the mobile device is seeking to handover to another of the plurality of wireless access points; determining the signal strength of a wireless link between said first wireless access point and the mobile device; sending a message to said management server, the message containing the determined signal strength and an identifier for the connected mobile device, monitoring for probe requests issued by the connected mobile device, indicative that the mobile device is seeking to handover to another of the plurality of wireless access points; determining the signal strength of a wireless link between said first wireless access point and the mobile device; sending a message to said management server, the message containing the determined signal strength and an identifier for the connected mobile device, the management server: receiving the message from the first wireless access point; storing the identifier for the mobile device and the determined signal strength in a data store, wherein the determined signal strength is stored as a threshold signal strength for handover for that mobile device, receiving the message from the first wireless access point; storing the identifier for the mobile device and the determined signal strength in a data store, wherein the determined signal strength is stored as a threshold signal strength for handover for that mobile device, at least one second wireless access point: receiving a probe request from said mobile device; sending a second message to the management server, including details of the probe request, an identifier for the mobile device and an observed signal strength, receiving a probe request from said mobile device; sending a second message to the management server, including details of the probe request, an identifier for the mobile device and an observed signal strength, receiving the second message from the at least one second wireless access point; retrieving the threshold signal strength associated with the mobile device from the data store; determining whether the observed signal strength between the at least one second wireless access point and the mobile device is above the stored threshold signal strength associated with said mobile device; if the observed signal strength is above the threshold signal strength, then instructing the second wireless access point to respond to the probe request, if the observed signal strength is below the threshold signal strength, then instructing the second wireless access point to ignore the probe request.