Abstract: The invention concerns a process and an apparatus to initiate the reversal of an inverter controlling the placement of a so-called hands-free telephone set in a reception mode or a transmission mode. According to the invention, the position of the inverter (8) is a function of the sign of the difference between the amplitudes of the integrated analog emitted signal and the integrated analog received signal. By preference, the received signal is drawn downstream (from the received-signal output) of the inverter, while the emitted signal is drawn upstream (from the emitted-signal input) of the inverter (8). A second received signal is drawn upstream of the inverter (from the received-signal input) so as to nullify the delay imparted to the change in position of the inverter if the amplitude of the corresponding integrated signal becomes significant.