G.723.1

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G.723.1 is an audio codec for voice that compresses voice audio in chunks of 30 milliseconds. A look-ahead of 7.5 ms duration is also used. Music or tones such as DTMF or fax tones cannot be transported reliably with this CODEC, and thus some other method such as G.711 or out-of-band methods should be used to transport these signals.

G.723.1 is mostly used in Voice over IP (VoIP) applications for its low bandwidth requirement. It became an ITU-T standard in 1995. The complexity of the algorithm is below 16 MIPS. 2.2 kilobytes of RAM is needed for codebooks.

There are two bit rates at which G.723.1 can operate:
- 6.3 kbit/s (using 24 byte chunks) using a MPC-MLQ algorithm (MOS 3.9)
- 5.3 kbit/s (using 20 byte chunks) using an ACELP algorithm (MOS 3.62)

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