I have an issue I’ve been experiencing for a while now, and let me explain my setup first, ask the question second, and explain the problem last.
First, I have a server with the following on a 4-channel T420P Digium PRI Card:
- Span-1: PRI Trunk to local, legacy Nortel PBX 
- Span-2: PRI Trunk from telecom provider 
- Span-3: PRI Trunk expansion of service from telecom provider in Span-2 
- Span-4: empty/skipped
My main question is about the “Sync/Clock Source” settings in the DAHDI Configuration, which I have noted their current settings in “[#]” brackets above. Which span should be set as the primary in this setup? And should the clock sync of the two, expanded PRI’s be set to the same?
The problem I am having is that when the third PRI is connected and when the server is under heavy call loads, the audio of the calls start to crackle with what sounds like static across the entire system. The server this is running on does need a hardware upgrade, but after trouble shooting through hardware configs and setting processor affinity to resolve a majority of problems, this is the last element of troubleshooting that I’m trying to take before pursuing a full hardware replacement.
I wanted to get some recommendations before I make any tests because recreating heavy call loads isn’t something I can anticipate in this environment and always hits the hardest when I’m not watching.
Any feedback is appreciated. Thanks!