QCELP-13 is a variable-rate codec operating at four bit rates and dynamically adjusting the rate depending on the source signal. Typical conversational speech yields an average data rate of around 6.6 kbps, and the codec can also trade a reduced average data rate for slightly reduced voice quality. The VoiceAge QCELP-13 (IS-733) implementation is fully compliant with the TIA-EIA-IS-733 technical requirements for use in wideband spread spectrum (CDMA) systems.
