TDM400P Sound Quality

Trying Asterisk for the first time.

A simple echo test in extensions.conf works fine, however the outgoing sound quality over the PSTN is extremely poor and completely unacceptable.

I’ve spent days on looking for IRQ issues etc, however I have not found any issues and nothing has changed. I have also disabled the VGA frame buffering and ensured that an X Server is not running.

Previously I tried a TDM410 and had perfect outgoing sound quality and nothing coming in, I suspect the card is faulty.

How hard can this be!?

Contact the vendor. For current, genuine, Digium products, start at (You will need the card serial number.)

I’m not sure whether or not your card is current.

re: Current Cards

The TDM400 was marked End of Life back in 2008. One of the reasons we moved away from that design was due to insurmountable (in that design) incompatibilities with modern chipsets that affected audio performance. The TDM410 addressed those concerns.

The TDM410 stopped being generally available back in 2014 and was replaced by the A4A, which improved upon the older card by offering, among other things, a better form factor and more robust (fully field-upgradeable) firmware management.