A communications server comprises a data receiver configured to receive status data indicating, for each communication terminal of a set of communication terminals, a current device status of that communication terminal; a terminal manager configured to assign each communication terminal of the set of communication terminals to one or more communication terminal groups in dependence upon the respective status data for that communication terminal; and a communications controller to control the transmission of communications data to each of the set of communication terminals in dependence upon the respective communication terminal group to which that communication terminal is assigned by the terminal manager.