Codec G729 configuration

Hi All,

We are evaluating to buy the g729 codec from digium, but for test, we need to buy a few licenses (no problem with that, we buy 2 for each country).

Here is the situation,
6 countries each one with its own elastix server and cisco 7940 phones.
1 country acting as a central node; this means that each of the other 6 have an IAX trunk to this central PBX.
when a user wants to call from one country to another they first need to dial 8 that takes the call to the central PBX, from there they need to mark 2 for one country and then the extension, for example if one user from Miami wants to call a user in spain from miami he dial 8 (central PBX) 2 (internal country code) and 5600 (extension in spain).
All this is working but the audio quality is really poor.
the question is i just bought 2 license for each country for g729 but none for the central PBX, do i need to install licensed codecs there to? how many?

maybe this is not the best config but it is what it is.

Thank you very much for the help!!

You might not need any codecs. It depends on whether anything in the configuration forces it to do transcoding. This can include monitor, whisper, local generation of tones, originates, etc.

Thank you David for the response, i just forgot that in the central PBX I have conference rooms that the people can use globally… if that the case i belive that we are going to need them.
is there any way I can see if the PBX is using the G729 Codec?
do i need to do anything special in the IAX Trunk to get the codecs work?

Thank You!

After you install the g729
This option is for outgoing voice stream only. It does not affect incoming stream that should be decoded automatically whatever the bitrate is.
in sip.conf or/and iax.conf configure the codec(s) either globally or under respective peer, for example:

too you can use the sip show channels command to monitor the codec used between active SIP channels

You need licenses for both encoding and decoding. However, sometimes streams can be passed through untouched.

I installed a few days ago the g729 codec on my Asterisk Box without any license following this link and is running smooth, but remember technically if you dont have license you will only be able to use the g729 codec as passthrough .

For passthrough, you only need the format module, which is part of the open source code.