G.729 Codec

Cut bandwidth usage without sacrificing voice quality using the G.729a codec from Digium.

5 out of 5

(1 review)
  • Buy Now

  • Certified

  • Supported


  • Allows Asterisk to transcode G.729a to/from any other Asterisk-supported format
  • Uses host CPU to perform transcoding - no expensive DSP hardware required.
  • Available for 32-bit and 64-bit Linux systems


  • Paid
  • $10 USD


The G.729a voice codec reduces the bandwidth used by each call, allowing more simultaneous calls over limited connections.  Each G.729 encoded call uses 13 Kbps in each direction -- 20% of the bandwidth required by G.711.  G.729 is idea for connections to limited bandwidth locations (remote offices, home offices) or for trunk connections over the public Internet. 

Digium offers an implementation of G.729 that is compatible with Asterisk and is properly licensed from the intellectual property rights and patent holders. The requirements of the GNU Public License (under which Asterisk is most commonly distributed) make this proprietary software codec incompatible from a licensing perspective. To resolve this license incompatibility, Digium grants an exception to the GPL for customers of this G.729 codec.
This software is licensed on a per-channel basis at $10 USD per channel. When you complete the webstore order, a license key will be generated and e-mailed to you, along with instructions for its use. Follow the G.729 installation instructions to register the channels you have purchased. Registration of your key locks the license key to the server on which it was registered.

Each Asterisk server that you want to perform G.729 transformations will require its own license key. Therefore, if you have Asterisk in multiple locations, then G.729 must be installed and licensed separately at each location.

Rather than the 64kbit/s required for a standard, uncompressed G.711 PCM audio data stream, the G.729 codec compresses the payload to 8kbit/s. Bandwidth calculations for a VoIP call should consider signaling and packet overhead as well, which varies according to network topology. In a typical Ethernet environment and utilizing the SIP or IAX signaling protocols, a G.711 call will consume about 87.2kbit/s while a typical G.729 compressed call will consume about 31.2kbit/s.

A practical example is the number of calls that may be carried across a standard 1.5 megabit/s T1 link. When using uncompressed G.711 audio, one can expect 18 concurrent calls across a T1. And, when using G.729 compression and Digium's IAX2 Trunking, instead of SIP, signaling protocol, one can expect about 140 concurrent calls across the same link.
Digium's implementation of the G.729 Codec in software allows Asterisk to transcode (compress and decompress) audio to and from formats other than G.729. Many business-class IP telephones and VoIP gateways include support for G.729. With the Digium G.729 Codec for Asterisk, those devices can now exchange calls with Asterisk directly.

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Reviewer: mjordan

over 2 years ago

G.729: still relevant!

Support Details

Digium provides case-based e-mail and phone support from Monday-Friday, 7am-8pm, CST/CDT (GM -6/-5).

In addition, Digium provides online documentation and knowledge base articles accessible from its website.

Other community-based support offerings are available including online mailing lists, an IRC channel and forums.

For links to each, please visit the Digium website

All new Digium telephony cards come with a 5 year warranty and are backed with Digium's Exceptional Satisfaction Policy. See Digium's website for more information about product warranties.

Support Contact Information

Digium, Inc


Digium®, Inc., the Asterisk® Company, created and is the innovative force behind Asterisk, the most widely used open source telephony software. Since its founding in 1999 by Mark Spencer, Digium has become the open source alternative to proprietary communication providers, with offerings that cost as much as 80 percent less. Digium offers Asterisk software free to the open source community and offers Switchvox, Digium's Unified Communications solution to power a broad family of products for small, medium and large businesses. The company's product line includes a wide range of telephony hardware and software to enable resellers and customers to implement turnkey VoIP systems or to design their own custom communications solutions. At Digium, we're changing the way businesses communicate.


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Digium Certified

Digium offers certification of selected products to ensure their interoperability with Certified Asterisk as well as Digium's other products. A Digium certified product provides an assurance of quality and interoperability of the product with Asterisk.