So I have a b400 card configured for DAHDI, and it seems to be working (i have an outbound route with two numbers and calls going to that seem to work fine). However when calling on that line I get intermittant static: its about 6 seconds long, and happens fairly regularly (maybe every minute or two). This doesn’t happen on straight SIP calls. I need to track down a handset to doublecheck the POTS line, but it seems like a server/card issue. But not sure what to look for in the logs regarding this.
Also, is there a way to see if there is a dial tone on the card from the CLI?
I had a problem like that with a card that wanted a LOT of IRQs. Check to see if your problem might coincide with (say) a recoverable hard drive read error or some other, similar “all hands on deck” sort of activity at the server.
Is it possible that the POTS line is also a DSL line. Maybe this is the source of the 6 seconds of static. Once you find an analog phone, plug it into your POTS line to determine if there is static on the line. Make sure the line is not connected to any other equipment. It would be ideal if you could test the line at the demarcation point. Hope this helps.
If that is the case, you need to put in a digital filter so get rid of the digital signals on the analog line.