OK to share irq between NIC and sound card?

I noticed that my sound card is sharing an irq with one of my Asterisk 1.2 box’s network cards. On about 1 in 20 incoming calls from my SIP provider, we can not understand the caller but hear only “buzzing” when they speak. They hear us fine. If they call right back, all is fine. I’ve tried pretty much everything to fix this including a fresh install on a new server. The provider is also stumped. Could this irq sharing cause trouble? I use the sound card to play a wav file over a speaker when calls come in and we have up to 4 calls at once.

Since you say you tried a new install on a new server I would say its safe to assume the server hardware is not at fault. IRQ issues are usually problems with the digital voice cards from Digium et.el. not network cards (unless the card is faulty but by swapping servers I assme you have tried two seperate network cards).

What about other hardware between the server and sip provider, network cables, switches, router, modems etc. Any way you can try swapping those out?

I did think of that and have replaced the only switch that’s common to all calls. I guess I can try a different port in my T1 router…