Marginal sound with digium tdm hardware and analog phones

I am using asterisk and digium hardware, and am experiencing marginal sound quality. I’m running a fedora core 3 system with a 3.2 GHz P4 and 1 GB RAM. I have a digium tdm31b with 3 fxs and 1 fxo interface. I have just ordinary analog phones connected to the fxs interfaces and the fxo interface connected to the telco. I hear clicks and spurious noise, and sometimes get brief dropouts. Some of the bundled sounds (like voicemail and record prompts) are somewhat distorted when playing. The phones sound fine when plugged in directly to the telco. I really did expect a lot better sound, considering I did not scrimp on any hardware purchases. Anybody got any ideas?

Have you tried to fre IRQ-s? You shuld remouve any PCI cards, USB ports (ewerything!) that you don’t use. Your TDM card shuld have free IRQ just for herself.

Please let me know the result.

Try disable your GUI completely. You should only be running in text mode. The PC should not be running any other server software other than what you need for Asterisk.