Abstract: A method for gain control of telephone sets having an electronic speech circuit and an apparatus for carrying out the method include a modulation current source. Two line terminals connect the modulation current source to a telephone line. A microphone amplifier has an input connected to a microphone terminal and an output controlling the modulation current source for generating a line signal. Signals are derived from the modulation current source and converted into mutually associated measurement signals and threshold value signals. The mutually associated measurement and threshold value signals are compared with one another. The gain of the microphone amplifier is regulated as a function of the result of the comparison.

Abstract: An electronic speech circuit configuration includes first and second line terminals to be connected to a telephone line. An AC circuit portion includes a modulator circuit for generating a line transmission current. A DC circuit portion supplies energy and generates a DC current/voltage characteristic curve. The DC circuit portion includes a reference potential source and a decoupling capacitor. A current sensing resistor is provided. A high-speed control amplifier has a control circuit and controls current through the current sensing resistor. A buffer capacitor is provided. Output terminals are connected to the buffer capacitor for the connection of external components. The DC circuit portion also includes a current toggle circuit connected upstream of the buffer capacitor. The current for feeding the buffer capacitor flows through the current sensing resistor connected to the first line terminal.