Abstract: The geolocation device comprises: a requester (10) arranged to obtain signaling data associating identifiers of mobile communication devices (6) and signaling identifiers, at least some of the signaling identifiers designating a location cell, a selector (12) arranged to determine a list of location cells neighboring a target location cell, based on the set of cells situated at a chosen distance from the target location cell, the chosen distance being defined in a metric manner or on the basis of the topology of the cellular network, a sorter (14) arranged to select from the requester's data (10) at least one mobile communication device identifier (9) detected as being associated with a signaling identifier relating to a location cell belonging to the list of neighboring location cells determined by the selector (12), and a tracker (16) arranged to launch active location cell monitoring of a mobile communication device (9) whose mobile device identifier has been selected by the sorter (14).