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"
NOTE: Even though the codec is installed, in use and exhibits no errors, the sipxconfig UI may not indicate it is aware the codecs are installed. If you follow all of these steps and get the correct output, consider the indicator in sipxconfig a temporary cosmetic one until it is fixed. As the FS binary changes, it is sometimes not always possible to keep up with the nuances of this binary installer and what sipxconfig needs from it.
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.