A system comprising: a location analytics server configured to receive, from one or more wireless sensing devices installed at a location to be observed, information about detected wireless devices , wherein the location analytics server is configured to analyze the information about the detected wireless devices to classify (S304), for each of the detected wireless devices , whether the respective wireless device is a visitor device or a passerby device, wherein classifying the respective wireless device is performed based on a location-specific configuration comprising at least one criterion to be satisfied for classifying the respective wireless device as a visitor device, wherein the at least one criterion is specifically adapted to the location , wherein the information about the detected wireless devices includes a signal strength observed for the respective wireless device and wherein the at least one criterion comprises a minimum signal strength required for classifying the respective wireless device as a visitor device, wherein the at least one criterion comprises a required minimum number of detections of the respective wireless device with the minimum signal strength within a predetermined time interval, wherein the information about the detected wireless devices includes a Media Access Control, MAC, address of the respective wireless device , the MAC address being indicative of a manufacturer and/or a device type of the respective wireless device , and wherein the minimum number of detections is set differently per manufacturer and/or device type of the respective wireless device . a location analytics server configured to receive, from one or more wireless sensing devices installed at a location to be observed, information about detected wireless devices , wherein the location analytics server is configured to analyze the information about the detected wireless devices to classify (S304), for each of the detected wireless devices , whether the respective wireless device is a visitor device or a passerby device, wherein classifying the respective wireless device is performed based on a location-specific configuration comprising at least one criterion to be satisfied for classifying the respective wireless device as a visitor device, wherein the at least one criterion is specifically adapted to the location , wherein the information about the detected wireless devices includes a signal strength observed for the respective wireless device and wherein the at least one criterion comprises a minimum signal strength required for classifying the respective wireless device as a visitor device, wherein the at least one criterion comprises a required minimum number of detections of the respective wireless device with the minimum signal strength within a predetermined time interval, wherein the information about the detected wireless devices includes a Media Access Control, MAC, address of the respective wireless device , the MAC address being indicative of a manufacturer and/or a device type of the respective wireless device , and wherein the minimum number of detections is set differently per manufacturer and/or device type of the respective wireless device . <EOS>