Counting the crowd at an event, know the pedestrian traffic in front of the window of a shop or detect billboards that attract potential new customers. The start-up TrenCube Guillaume Lebret invented a « Google Analytics » in the real world : a case « sensor customer behavior. » This unit automatically detects smartphones around a specific place, to several tens of meters around. Only mobile with WiFi turned on are recorded anonymously by the machine. The housing is able to recognize a person who has already passed in the area. The numbers thus possible to obtain a guaranteed minimum number of passes before a shop or at a parade.