Abstract: Device for performing the "hands-free" function in a telephone set associating the gain switching and echo cancellation functions. This device is characterized in that it comprises a gain switch and an echo canceller, said switch having in the emission and reception channels a circuit for measuring the amplitude of the signals present on these channels, a checking circuit for determining the state of the telephone set (emission, reception, rest,) a calculating member controlled by the checking circuit, variable attenuators controlled by the calculating member, said calculating member evaluating, as a function of the relative amplitudes of the signals in emission and in reception, the echo cancellation performances obtained by the device and adjusting as a function thereof the variable attenuators in each channel, so that the overall attenuation in the loop always assumes the minimum value ensuring the stability of the system.