Implantable medical device (10) having control unit (20) connected to bidirectional wireless interface (18) and magnetic interface (16). Bidirectional wireless interface configured for bidirectional wireless data transmission via alternating electric field between medical device and an external device and may assume at least one OFF and one ON state, whereby wireless data transmission is possible only in ON state and function interface requires little or no energy in OFF state. Magnetic interface configured to constantly receive control signals transmitted via an alternating magnetic field from the external device. Magnetic interface configured to receive/process a data transmission start signal, such that magnetic interface or control unit generates a wireless interface activation. The bidirectional wireless interface is at least indirectly connected to the magnetic interface and is configured to switch from OFF to ON state in response to the wireless interface activation signal.