The invention concerns an installation for managing a pay parking facility for vehicles comprising a plurality of vehicle immobilizing devices (1) for immobilizing contravening vehicles, and wherein an unlocking code (8) is delivered to the user (0) after payment of the amount corresponding to the unlocking of the vehicle immobilizing device. Upon a request for unlocking from the user (0), the parking terminal (2) is adapted to set up a session corresponding to the unlocking of the vehicle immobilizing device with the payment means (3), to communicate to the server (4) of the identifier of the immobilizing device to be unlocked after the payment session has been validated while the server (4) is adapted to receive the identifier (7) thus input and to deliver in response the unlocking code (8) associated with the destination of the terminal to unlock the immobilizing device in question.