How to convert g711 call to g729

hi there,

i have asterisk server 1.4 and 1.8 on Pentium4 processor What configuration I need to convert g711 to g729.

call coming to my asterisk server in g711 format i need dial that call in g729 format.
this possible with Transcoding or Pass-Thru and with g729 codec binary that free for testing perpose.

thanks in advance

Pass through will only work if both phones support G.729.

There are no legal free licenses for G.729 codecs. One that claims to be free, purports to use the GPL, but is based on code that has a no commercial use restriction, which voids the GPL. In any case, if you are in a country that implements software patents, I think the only dispensation is for learning about the codec, not for evaluation or production use.

The Digium G.729 codec licence really is quite cheap, if you only need one for evaluation.

In practice, there is little benefit in using G.729 unless you are handling large numbers of calls over limited bandwidth. If you are doing that, you probably also need to use IAX trunks.

Hi David,

Thanks for replay for needful explanation.

can you further explain me difference between Passthrough mode and Transcoded mode.
Which is free and use to convert g711 call to g729.


Pass through is free to use but does not transcode.

Transcoded mode transcodes, but is not free to use.

In pass through mode, both parties must have exactly the same codec, there must be no need for Asterisk to look for inband DTMF, or record the call, there must be no need for Asterisk to generate tones, and any voice announcements must have been pre-recorded using the codec. Pass through means that the media is forwarded without Asterisk understanding it, or doing anything with it.

Why do you absolutely need G.729?

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