The MSM7603/7603B is an improved version of the MSM7602 with basically the same configuration, and offers twice the cancelable echo delay time of the MSM7602. The MSM7603B I/O interface allows switching between m-law PCM and A-law PCM. The MSM7603/7603B is a low-power CMOS IC device for canceling echo (in an acoustic system or telephone line) generated in a speech path. Echo is canceled, in digital signal processing, by estimating the echo path and generating a pseudo echo signal.