G729

Introduction

G.729 is a toll-quality, low-bandwidth audio codec supported by many VoIP providers. The voice quality of a G.729-encoded call is about the same as that of G.711, the codec used for standard PSTN calls. However, the amount of bandwidth needed to carry a G.729 call is much lower than that for a G.711 call. Enterprises using G.729 will make more efficient use of available network bandwidth. G.729 uses roughly 1/8th of the bandwidth of a G.711 (8 kbit/s vs 64 kbit/s).

G.729 is available in two ways:

Passthrough Transcoding

The passthrough method does not require licensing, however it has some limitations. For transcoding method G.729 license is necessary. Freeswitch offers a module and G729 license for transcoding G.729. Freeswitch's G.729 module supports Annex A and Annex B.

Obtaining License

Licences can be purchased from the FreeSWITCH website - see the G.729 tab at the top of the page.
Pricing is $10 per channel.

A single licence provides you with one encoder and one decoder, which is enough for bridging one call.

Licences are only required for channels performing transcoding (for bridging calls a leg uses G.729 and a different leg uses a different codec, and for applications which need to process media). Bridged channels where G.729 is on all legs still use pass-through mode, so that they do not consume a licence.

G.729 Module Installation

Download the fsg729-xxx-installer file from http://files.freeswitch.org/g729

cd /usr/tmp
wget http://files.freeswitch.org/g729/fsg729-167-installer
sh ./fsg729-167-installer

Note: fsg729-139-installer did not work with FreeSWITCH Version 1.0.head (1), try 136, the previous one if it gave error such as (var/log/sipxpbx/freeswitch.log):

[xecsuser:CRIT] switch_loadable_module.c:882 Error Loading module /usr/local/freeswitch/mod/mod_com_g729.so
*/usr/local/freeswitch/mod/mod_com_g729.so: undefined symbol: g729_decode_free*
-ERR [xecsuser:module load file routine returned an error]

G.729 License Activitation

Run the license validator:

cd /usr/local/freeswitch/bin/
./validator

Enter the sales code you received from Freeswitch, licenses.zip file will be generated in the current directory. Unzip this file into /etc/freeswitch/
After unzip there will be xxxxxxxxxxxxxxxx.conf in the /etc/freeswitch

Freeswitch Configuration

Sipxconfig should detect this module and add G.729 codec as default to the following:

System/Servers/Server nnn/Media Services/Codec
System/Servers/Server nnn/SIP trunking/SIP/Permitted Codecs (TBD: I don't think this applies – douglas)
Click "Apply" button on each page even though you haven't changed anything to trigger config change and prompt to restart Media Services. Go ahead and restart "Media Services"

freeswitch_licence_server is automatically started by mod_com_g729 if freeswitch is started by root, but in sipXecs freeswitch is not started by root. So you have to start freeswitch_license_server manually: /usr/sbin/freeswitch_license_server

cd /usr/sbin
./freeswitch_licence_server

Putting this in init.d worked for me to make it start with the server:

Create an entry in /etc/rc.d/init.d (ex: G729app) and paste this in:

#!/bin/sh
# description: FS_LIC_SVR
# chkconfig: 2345 99 00

case "$1" in
'start')
        /usr/sbin/freeswitch_licence_server
        touch /var/lock/subsys/G729app
        ;;
'stop')
        rm -f /var/lock/subsys/G729app
        ;;
*)
        echo "Usage: $0 { start | stop }"
        ;;
esac
exit 0

if the license server is not working or the license is invalid, freeswitch will complain (var/log/sipxpbx/freeswitch.log):

[ERR] mod_com_g729.c:113 ENCODER CREATE FAILED- 0x9c213b0 (nil)
[ERR] switch_core_io.c:882 Codec G.729 encoder error!

Monitoring License

Run the freeswitch console:

cd /usr/local/freeswitch/bin
./fs_cli

(First, unload the passthru mod, and licensed one, and reload the licensed one)

 freeswitch@internal>unload mod_g729
 freeswitch@internal>unload mod_com_g729
 freeswitch@internal>load mod_com_g729

Here are the g729 commands to run from the fs_cli. These are not available until you load the mod_com_g729 module. I think the FS docs allude to a g729_status, 
which probably worked on the older binaries, but has since been replaced with these. I think the docs on their site probably need to be changed. Once the mod_com_g729
has successfully loaded, you will see the following option from the "help" command of the fs_cli:


g729_available,,return true or false if g729 is available,mod_com_g729
g729_count,,return permitted license count,mod_com_g729
g729_info,,return current g729 usage details,mod_com_g729
g729_used,,return in use encoder and decoders,mod_com_g729

 freeswitch@internal>g729_available
 true
 freeswitch@internal>g729_count
 2
 freeswitch@internal>g729_info
 Permitted G729 channels: 2
 Encoders in use: 0
 Decoders in use: 0
 freeswitch@internal>g729_used
 0:0

OK, but WAIT, we are not done! Now we have to activate the licenses in sipx media server and restart media server. We also need to look in /etc/sipxpbx/freeswitch/modules.conf.xml.vm and edit the section "Cedec Interfaces" to say:

#if(${codecG729})
    <load module="mod_com_g729"/>
#else
    <!--< load module="mod_g729"/> -->
#end

OK, now edit /etc/sipxpbx/freeswitch/conf/autoload_configs/modules.conf.xml, and in the area for codec interfaces make sure the line for G729 exists and states the following:

<load module="mod_com_g729"/>

Now restart FreeSWITCH in sipx with
sipxproc -r FreeSWITCH
and monitor it to see if it successfully runs with
sipxproc --state

Now use the commands above when g729 is in use to see if it is being used and how it performs.