A system for controlling a user's access to an electrical device (314). The system includes an interchangeable unit (200) operable for wireless communication with a mobile communications device (10), a power control unit (300) having a communications interface (302), and an external network processor configured to receive a verification request to verify that a user of the mobile communications device is authorized to access the interchangeable unit. The external network processor is configured to send to the mobile communications device an authorization confirmation after the user's access to the interchangeable unit is verified as being authorized.