Abstract: A parking lot control system using a third-party system, having at least one transmitting device emitting an entry ticket including first and second sets of reading data, the first set of data being read by the third-party system which emits an exit password upon fulfillment of parking lot exit conditions. The control system also includes: a processing unit which communicates with the third-party system in order to receive the exit password therefrom, and at least one exit validation device which receives the exit password from the processing unit and reads the first and/or second set of data on the entry ticket in order to allow the release of vehicles having a ticket corresponding to the exit password generated by the third-party system. If no exit password is received, the validation device can operate redundantly in order to allow the release of vehicles meeting the exit conditions.