One way Static on CM6.1.5 only on inbound calls from a CMM ws-x6600

[gbchristy]

I have a one way static issue, random callers (1-2 a day are reported, some days none are) can't hear the remote side well because of static on the call.  The remote side can not hear the static.

We have no VAD active in the Call Manager.

Anyone seen this before?

I have been running this Call Manager for almost 2 years now with no issues, these just started about a month ago.

[William Bell]

Geoff,

The observation of intermittment behavior could point to a physical layer issue. For instance, let's take a basic example of four PRIs configured as a single trunk group where ingress calls hunt sequentially from 1 to 4. If you only notice the issue when running at 75% utilization then your root cause could be a physical layer issue on the 4th PRI.

Another variation is a faulty DSP, where calls only flake out when landing on DS-0s mapped to a faulty DSP.

One way to confirm this theory is to isolate DS-1s and DS-0s and test. Start with testing physical cabling and then a call-by-call on DS-0s. Another (more efficient) approach is to capture a faulty call in process and then use some IOS show commands to identify trunk/timeslot.

I did a write up on a method to test individual DS-1 and DS-0s here:

http://www.netcraftsmen.net/resources/blogs/test-voice-gateways-part-1-seizing-a-t1e1-voice-circuit.html

HTH.

Regards,

Bill