An access control system receives a device-specific identifier of a mobile electronic device. A memory device stores the identifier as belonging to a user present in a public zone. An image processing device generates from a camera image produced by a camera a real-time template for facial features of the user present when the user present requests access to an access-restricted zone, and searches user profiles stored in a database for a reference template that matches the real-time template to a specified degree, wherein a user profile is searched only if it is assigned to a present user based on a stored identifier, wherein in the case of a match, the system grants the user access to the access-restricted zone and denies access when there is no match.