A user of a mobile communication apparatus (160) seeks permission to operate an access control device (110) by placing an active mobile power source unit (150), which is controlled by the mobile communication apparatus (160), within an operation range of a wireless power transmission interface (116) in the access control device (110). In response thereto, a wireless power transfer link is established between the mobile power source unit (150) and the access control device (110). Thereafter, a wireless communication link (WL2) is established between the mobile communication apparatus (160) and the access control device (110). Data are then exchanged between the access control device (110) and the mobile communication apparatus (160) over the wireless communication link (WL2). The exchanged data pertain to at least one access-related service implementable via the access control device (110); and provided that the user is authorized, the requested services are effected.