iLBC (internet Low Bitrate Codec) is a FREE speech codec suitable for
robust voice communication over IP. The codec is designed for narrow
band speech and results in a payload bit rate of 13.33 kbit/s with an
encoding frame length of 30 ms and 15.20 kbps with an encoding length
of 20 ms. The iLBC codec enables graceful speech quality degradation in
the case of lost frames, which occurs in connection with lost or
delayed IP packets.