Complete Protocol dictionary, glossary and reference
G.721 is a 32 kbps Adaptive Differential Pulse Code Modulation (ADPCM) speech compression algorithm. The sampling rate is 8 KHz. G.721 produces toll quality speech. With transmission error rates higher than 10.4, the perceived quality of G.721 is better than G.711. G.721 is the first ADPCM standard. Later came the standards of G.726 and G.727 for 40, 32, 24 and 16 kbps.