[HELP] bad quality in voicemail

I have a strange problem with the voicemail feature.
We are using AVM C4 boards to connect to our legacy PBX.

SIP <-> Capi calls work with good quality and so does the monitoring
of such connections.

A voicemail recorded from an incoming SIP also works fine.

The trouble begins when a CAPI (ZAP?) call is speaking to the voicemail.
Parts of the words spoken are simply missing. Sounds a bit like a too high

We already did the following:

  • Check if disks run in DMA-Mode.
  • Disable all unused peripherals like serial und parallel io
  • Remove all PCI-boards but the C4
  • Set the IRQ to 3 or 4 or 7 explicitly via the bios
  • Play with the silencethreshold parameter in voicemail.conf and restart asterisk

None of these had any noticable influence on our problem.
Is there maybe a known problem with the voicemail code ?

The System is a 1.8 GHz Athlon with 512MB. The CPU is nearly always 0 in our
testing szenario. We use Asterisk 1.0.7 compiled from source.

I have already posted this in a german forum but got no solution which led to the
IRQ and board switching.

Thanks for any comments.

Hello tjwan.
I had the same problem till I change in the capi.conf file the option:

You have to disallow echocancel to make it work fine.

Tell me what it made by your side.