ITU G.723.1

G.723.1 is an ITU standard codec.

Its reasonably low bit rate (6.3Kbps or 5.3Kbps) and used in the H.323 standard
Use of this codec in a product requires licencing by Sipro Lab Telecom.

Asterisk server supports it in pass-thru mode.

Comments on G.723.1 vs G.729 (the original page is gone, so this link points to an archive.org copy) on Asterisk mailing list

• Codecs
• ITU G series recommendations