ITU G.729

G.729 is an ITU standard codec.
Has two main flavors: A and B, see the ITU G series page for more info.

It offers toll quality speech at a reasonably low bit rate of 8Kbps. However, it is a rather “costly” codec in terms of CPU processing time, therefore some VoIP phones and adapters (notably the Linksys/Sipura/Cisco brands) can only handle one G.729 call (channel) at a time. This can cause calls to fail if the user attempts to use three-way calling, or place simultaneous calls on both lines of a two-line device, and G.729 is the only allowed codec.

Use of this codec in a product requires licensing. Licenses can be purchased from a company that re-sells G.729 licenses such as:

There are some free for non-commercial experimental use implementations for G.729

http://www.readytechnology.co.uk/open/ipp-codecs-g729-g723.1/ for Asterisk based on Intel libraries
VoiceAge Windows executable
Intel Windows and Linux
The ITU has reference source code available.
- If your are not ITU member and want to download reference code for free:
  - Go to ITU Electronic Bookshop;
  - Select option #2: “I wish to REGISTER in order to download up to three (3) ITU Recommendations free of charge”;
  - Receive mail with your access code.
- Select recommendation at https://www.itu.int/rec/T-REC-G.729/e
- Select language and format
- Enter Login/Special ID* and Password and press Login.
- Press button “Download …..”
- NOTE: The descriptions for items with source code say something about “diskettes”.