Enhanced Variable Rate Codec

EVRC (which stands for Enhanced Variable Rate CODEC) is a speech codec used by CDMA networks. It was developed in 1995 to replace previous codec QCELP which was of worse quality. EVRC uses RCELP technology, which improves speech quality with lower bit rates. EVRC supports three source rates of 9.6 kbit/s (full rate), 4.8 kbit/s (half rate) and 1.2 kbit/s (eight rate). The lowest rate is not meant for speech signals, but back ground noise. Due to source controlled nature of the codec the average bit rate varies based on network conditions, but is usually around 6 kbit/s.

EVRC was replaced by SMV which retained the speech quality and at the same time improved network capacity.