An access control system comprises a plurality of access control devices in each of which is stored an access code. Specific access codes and access rights for a plurality of access control devices are transmitted from an access control central unit over a mobile radio network to the mobile communication terminal of a user. Transmitted to the mobile communication terminal by an access control device to be passed is an access control device identification. In the mobile communication terminal, on the basis of the received identification, the access code and the access rights for the access control device to be passed are determined, and are transmitted to the access control device. The access control device clears the user for access if the received access rights suffice and the received access code agrees with the stored access code.