Codecs used in telephone networks in the United States have a -law companding characteristic solely designed for the purpose of transmitting voice signals [1, 2]. These -law codecs are not well suited for the latest generation of high-speed digital voiceband modems requiring PCM data transmission at the quantization levels of the codec [3, 4, 5, 6, 7, 8, 9]. In this paper, we have shown that us...