control of the operation of mobile communication equipment is provided in a power - off state , wherein a part of the mobile communication equipment is kept in operation for receiving and analyzing at least one of a set of excitation signals . only a first part of the mobile communication equipment , which essentially consists of timing means , is kept in operation continuously . a second part of the mobile communication equipment , provided for receiving and analyzing the signals , is controlled by means of the first part to operate and analyze the signals during specified time intervals , and to be inoperative at another time . power for a radio frequency transmitter and receiver of the second part is switched off during the power - off state . analysis of the signals is accomplished during the power - off state .