Method for operating an access control system which comprises an electronic lock having an active and an inactive state on an access-restricted zone, a data processing device with a database which stores the state of the electronic lock, and a user file in which a user is assigned at least one access authorization to an access-restricted zone, and comprises a mobile electronic device to be carried by the user for a communication with the electronic lock and the data processing device, wherein the method comprises the following steps: receiving a data signal sent out by the electronic lock by the mobile electronic device when it is in the radio range of the electronic lock, wherein the data signal comprises a lock identifier and a lock state designator, wherein the lock state designator indicates the active state or the inactive state of the electronic lock; generating a server message by the mobile electronic device wherein the server message comprises the lock identifier and a device identifier of the mobile electronic device; sending the server message by the mobile electronic device to the data processing device by means of a first radio transmission; storing the state of the electronic lock in the data processing device based on an evaluation of the lock state designator, wherein the lock state designator is included in the server message which is received by the data processing device; generating a confirmation message by the data processing device, wherein the confirmation message: is generated depending on a result of an examination by the data processing device using the stored state of the electronic lock, wherein the result indicates the active state or the inactive state of the electronic lock, contains an electronic code for activating the electronic lock, if the electronic lock is in the inactive state and the device identifier in the user file is assigned to the lock identifier, and contains a user message if the electronic lock is in the active state or the user has no access authorization to the access-restricted zone assigned to the electronic lock; and receiving the confirmation message by the mobile electronic device by means of a second radio transmission. receiving a data signal sent out by the electronic lock by the mobile electronic device when it is in the radio range of the electronic lock, wherein the data signal comprises a lock identifier and a lock state designator, wherein the lock state designator indicates the active state or the inactive state of the electronic lock; generating a server message by the mobile electronic device wherein the server message comprises the lock identifier and a device identifier of the mobile electronic device; sending the server message by the mobile electronic device to the data processing device by means of a first radio transmission; storing the state of the electronic lock in the data processing device based on an evaluation of the lock state designator, wherein the lock state designator is included in the server message which is received by the data processing device; generating a confirmation message by the data processing device, wherein the confirmation message: is generated depending on a result of an examination by the data processing device using the stored state of the electronic lock, wherein the result indicates the active state or the inactive state of the electronic lock, contains an electronic code for activating the electronic lock, if the electronic lock is in the inactive state and the device identifier in the user file is assigned to the lock identifier, and contains a user message if the electronic lock is in the active state or the user has no access authorization to the access-restricted zone assigned to the electronic lock; and receiving the confirmation message by the mobile electronic device by means of a second radio transmission. is generated depending on a result of an examination by the data processing device using the stored state of the electronic lock, wherein the result indicates the active state or the inactive state of the electronic lock, contains an electronic code for activating the electronic lock, if the electronic lock is in the inactive state and the device identifier in the user file is assigned to the lock identifier, and contains a user message if the electronic lock is in the active state or the user has no access authorization to the access-restricted zone assigned to the electronic lock; and receiving the confirmation message by the mobile electronic device by means of a second radio transmission.