The invention relates to a cellular phone (10) for remotely controlling at least one function of a security device (12) of a motor vehicle (11). The cellular phone (10) has a first transceiver unit (14), whereby a connection can be established to a cellular network (16). According to the invention, the cellular phone (10) has a second transceiver unit (18), by means of which a first radio signal (20) can be received. The cellular phone (10) can be switched into an active mode by means of the received first radio signal (20), and a second radio signal (22) with an authorization code (21) can be transmitted by means of the second transceiver unit (18) in the switched active mode in order to control the function of the security device (12).