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 Asterisk cmd 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 Asterisk cmd Dial
Configuration for the SIP channel
sip.conf needs the following:
[general]
disallow=all
allow=g729
allow=ulaw
allow=alaw
See also:
- Asterisk | FAQ | Tips & Tricks
July 26, 2017
Phone System 