Asterisk G.729 pass-thru

How to use the G.729 codec in pass-thru mode in Asterisk

"Pass-thru" means that if you were, for example, using two phones which both have inbuilt support for g729 codec. You can let them talk to each other in g729 format, without asterisk having to transcode (which requires a license)

G.729 may require a license per channel unless it is used in pass-thru mode.

If no license is required, you can download the Open Source implementation or binaries for Linux and FreeBSD.

Contrary to what was on this page before, access to Voicemail requires only a few configuration tweaks in pass-thru mode:

- set format=g729 (and only format=g729) in voicemail.conf
- set maxsilence=0 in voicemail.conf

Detecting silence in Asterisk means that you need access to the stream in slin, which requires transcoding. This setting will disable that detection.

In order to ensure that it is used in this mode, pay attention to the configuration:
no T,t or monitor in the dialplan, application Dial

Configuration for the SIP channel

sip.conf needs the following:


See also:

Created by: flavour, Last modification: Wed 16 of May, 2007 (18:25 UTC) by riksta
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