An access control system and a method for operating an access control system are provided. The access control system includes an access control device. The method provides a step for initiating the transmission of the advertising signal by a communication module of the access control device, the advertising signal being received by a mobile device. The method provides a step for automatically receiving an access credential from the mobile device to the communication module of the access control device. The method provides a step for comparing, in an authentication module, the access credential with an authorized access credential (e.g., stored in a memory of the access control device).