Abstract: There is provided a method of controlling battery usage of a first mobile device in a monitoring system for monitoring a plurality of mobile devices which are monitored at a server, the system comprising the server and the plurality of mobile devices monitored at the server, the plurality of mobile devices including the first mobile device, the first mobile device including a battery, the method comprising the steps of: (i) each mobile device acquiring location data; (ii) each mobile device sending the acquired location data to the server via a telecommunications network; (iii) the first mobile device receiving an instruction from the server to adjust how often the first mobile device reports location data to the server, so as to control a battery usage of the first mobile device.

Abstract: There is provided a method of generating an alert message in a monitoring system for monitoring a plurality of mobile devices registered at a server, the system comprising the server and the plurality of mobile devices registered at the server, the plurality of mobile devices including a first mobile device, the method comprising the steps of: (i) each mobile device acquiring location data; (ii) each mobile device sending the acquired location data to the server via a telecommunications network; (iii) the server storing a time series of location data for each device; (iv) the server extrapolating a location of the first mobile device, and (v) the server generating the alert message which identifies the first mobile device in response to an extrapolated position of the first mobile device satisfying a condition.