Choppy Voice Mail, MOH and IVR announcement in PIAF purple 1.7
We have seen some reports about packet loss/choppy audio when playing back Voice Mail, MOH, and IVR anouncement in PIAF purple line. This issue only impacted PIAF purple 1.7 with Asterisk 1.8 starting with Asterisk version 1.8.2.0 to 1.8.3.0 ONLY.
One of the reason was during those version, PIAF choose to configure the asterisk timing to use pthread timer due to some issue with dahdi timer between 1.8.2.0 to 1.8.3.0 Astersik build. The pthread timer does not work well with our virtualization platform.
We have fixed this issue. Our latest PIAF Purple 1.7 with asterisk 1.5.6.0 has been fixed to use dahdi timer which does provide realible timer in our platform. If you experience similiar issue, we encourage you to ask for a rebuild to PIAF Purple 1.7 with asterisk 1.5.6.0 or later.
Should you like to keep your existing, please ensure that you do not use ptherad timer. You may disable pthread timer by adding the following line in your /etc/asterisk/module.conf "noload=>res_timing_pthread.so". In addition, you remove or comment out "noload=>res_timing_dahdi.so" in the /etc/asterisk/module.conf. You will need to restart your Asterisk after making this changes. If your current Asterisk version is between 1.8.2.0 and 1.8.3.0, you may encounter other issue due to dahdi timer issue.
In addition, we have also tuned our network buffer a little better in our PIAF Purple 1.7 with asterisk 1.5.6.0 image or later. If you like to take advantage of this optimization, you may also request a rebuild to Purple 1.7 with asterisk 1.5.6.0. If you like to do this manually in your exsiting system, you may add the following parameter in /etc/sysctl.conf
net.core.rmem_max = 8388608
net.core.rmem_default = 1048678
You will need to reboot the system after you make the changes.
Update: 1/8/2012
If you run PIAF purple on our system and still experience this issue, please try the following additional steps.
1. edit your /etc/sysctl.conf file. Change a line xen.independent_wallclock = 1 to xen.independent_wallclock = 0
2. type chkconfig ntpd off <enter> (you must do this).
3. reboot (you also must reboot)