Abstract: A method of configuring a lock control unit of an access control system, the lock control unit having associated with it a lock control unit identifier and an electronic key, the lock control unit comprising means for wireless communication via a wireless communications channel with a user mobile unit, and adapted to receive an a data item indicative of an electronic key from a user mobile unit, to verify a received electronic key and, subject to successful verification, to activate the lock mechanism, 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 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