A method of configuring a lock control unit of an access control system, the lock control unit being operationally connected to a lock mechanism for securing a location, the lock control unit having associated with it a lock control unit identifier and electronic key verification data, the lock control unit comprising means for wireless communication via a wireless communications channel with a user mobile unit, and adapted to receive a data item indicative of an electronic key from a user mobile unit, to verify a received electronic key based on the electronic key verification data and, subject to successful verification, to activate the lock mechanism, wherein the configuration process also comprises the association of the lock control unit with the location, the method comprising performing the following steps by a technician mobile unit: • receiving a message from an access control management system, the message comprising an address indicative of the location; • detecting, at the location, one or more lock control units communicating via the wireless communications channel in a proximity of the technician mobile unit; and receiving from each detected lock control unit a respective lock control unit identifier; • identifying, based on the received lock control unit identifiers, the lock control unit connected to the lock mechanism, by determining which of the lock control units is not yet associated with the location; • sending the lock control unit identifier indicative of the lock control unit identified by the technician mobile unit to the access control management system; • receiving, from the access control management system, an electronic key associated with the lock control unit identifier; • sending the electronic key and one or more commands to the lock control unit causing the lock control unit to perform one or more configuration steps; » sending a message from the technician mobile unit to the access control management system, the message being indicative of a completion of the configuration steps; wherein the method further comprises associating, by the access control management system and responsive to the message indicative of a completion of the configuration steps, the lock control unit identifier of the lock control unit connected to the lock mechanism with the address of the location. • receiving a message from an access control management system, the message comprising an address indicative of the location; • detecting, at the location, one or more lock control units communicating via the wireless communications channel in a proximity of the technician mobile unit; and receiving from each detected lock control unit a respective lock control unit identifier; • identifying, based on the received lock control unit identifiers, the lock control unit connected to the lock mechanism, by determining which of the lock control units is not yet associated with the location; • sending the lock control unit identifier indicative of the lock control unit identified by the technician mobile unit to the access control management system; • receiving, from the access control management system, an electronic key associated with the lock control unit identifier; • sending the electronic key and one or more commands to the lock control unit causing the lock control unit to perform one or more configuration steps; » sending a message from the technician mobile unit to the access control management system, the message being indicative of a completion of the configuration steps; <EOS>