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Introduction

The G.729 codec is an audio data compression algorithm for voice that compresses digital voice in packets of 10 milliseconds duration. It is officially described as Coding of speech at 8 kbit/s using conjugate-structure algebraic-code-excited linear prediction.

Because of its low bandwidth requirements, G.729 is mostly used in Voice over Internet Protocol (VoIP) applications (such as Skype) where bandwidth must be conserved. Standard G.729 operates at a bit rate of 8 kbit/s, but there are extensions, which provide rates of 6.4 kbit/s (Annex D, F, H, I, C+) and 11.8 kbit/s (Annex E, G, H, I, C+) for worse and better speech quality, respectively.

G.729 has been extended with various features, commonly designated as G.729a and G.729b.

DTMF tones, Fax transmissions, and high-quality audio cannot be transported reliably with this codec. DTMF requires the use of the RTP Payload for DTMF Digits, Telephony Tones, and Telephony Signals as specified in RFC 2833.


The G,729 codec is also one of the few paid codecs. The license price is included in the Gigaset phones.


Number of G.729 codecs in the Gigaset devices.

DeviceNumber of G.729 codecs
Maxwell 3/B2
Maxwell 1012
N510 IP pro4
N720 IP pro30
DX8004*


* The codecs are activated online, when no internet connection is available the codec cannot be used.

N720 G.729 codec activation

From software 105 or higher.

Codec is default enabled for 30 simultaneous channels.

Until software 105

To activate the G.729 codec in the N720 open the web-interface of the N720.

Go to: Settings - Telephony and click on "Activate G.729 codec"



When the codecs are activated, you will see on the same page the new option: "Enable Annex B for codec G.729"




Maxwell 3/B Annex B

From software 2.13 or higher, the G.729 Annex B option enable/disable is implemented.

To change the setting, in the web-interface go to:

  • Settings - Telephony - Audio
  • Add the codec G.729 to the Selected codecs
  • Select the codec G.729
  • The option G.729 Annex B will be visible in the web-interface.


Parameter nameValue:minValue:maxValue: allowed
SIP.G729.AnnexB010 = Do not use Annex B (default)
1 = use Annex B 
Example:<param name="SIP.G729.AnnexB" value="1"/>


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