An automatic sidetone controller for a digital telecom device, such as a headset or head-set adapter having a transmit (TX) channel, a receive (RX) channel, and circuitry for generating a sidetone signal by coupling a portion of a signal on the TX channel onto the RX channel via a sidetone path, is operable to detect when the TX channel of the device is active and inactive and to respectively activate and deactivate the sidetone path in response thereto without need for manual intervention by the user.