The commercial and standardized vocoder types include 4.8 Kbps /2.4 Kbps Improved Multi Band Excitation coder, 4.8 ~ 8 Kbps Department of Defense Code Excited Linear Prediction coder, 8 Kbps Vector Sum Excited Linear Prediction coder, 8 Kbps Qualcomm CELP coder and 16 Kbps Low Delay CELP coder [35-40].