Timing problems

I am experiencing choppy voice with the playback of recorded messages. I opened a ticket with Digium support and was told that there is a known problem with the ztdummy module that causes the voice choppiness. He unloaded the ztdummy module and the voice quality got much better.

Unfortunately, that broke the conferencing. Now when I dial into a conference bridge, it will not accept the PIN number. I get an invalid PIN error no matter what PIN I enter.

The digium support tech is now telling me that ztdummy is not intended to be used in production and the only way to fix this problem is to buy a digium hardware card and install it in the system to get an accurate clock.

Has anyone else experienced this problem and if so, how did you fix it? Is buying hardware the only option? We are 100% VoIP and it seems like a waste of $$ to buy a telco interface card for our asterisk server when we do not intend on ever connecting to a PRI or traditional analog phones.


try a cheapy x100p clone card, perhaps?

There’s also the zaprtc (comes with bristuff?) that you could try.


If you upgrade your kernel to 2.6.13 or greater, ztdummy can then get a more reliable timing source from the kernel and should get rid of any choppiness. If this isn’t an option you will need a zaptel card.