A CODEC circuit for POTS system comprises a digital circuit for outputting a digital control signal having a first bit width, the digital control signal being indicative of a voltage to be applied to a POTS subscriber line pair. Further, the CODEC comprises a noise shaper coupled to an output of the digital circuit for generating a noise-shaped control signal and a digital-to-analog converter coupled to an output of the noise shaper, the input of the digital-to-analog converter having a second bit width being larger than 1 and smaller than the first bit width.