ITU recommendation G.728 is a standard for voice codecs. It works with Low Delay, Code Excited Linear Prediction (LD-CELP) and transmission rates of 16 kbit/s. The transmitted frequency band of 300 Hz to 3.4 kHz corresponds to that of telephony. The speech quality of the speech codec has an MOS value of 4.2, i.e. almost ISDN quality, and the delay time is 1.25 ms.