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Call Manager 3.1.2C - 6608 - Hum on PRI's

I have 2 installed locations on the latest version of Call Manager (3.1.2C) and current firmware loads that both have had Static and very loud hum coming in on ISDN PRI's attached to the 6608 blade of a 6500. Has anyone else experienced this. If you reset the Gateway from Call Manager problem clears for days before recurrence. More prevelant under high traffic conditions.


Re: Call Manager 3.1.2C - 6608 - Hum on PRI's

Often times complex troubleshooting issues are best addressed in an interactive session with one of our trained technical assistance engineers. While other forum users may be able to help, it’s often difficult to do so for this type of issue.

To utilize the resources at our Technical Assistance Center, please visit and to open a case with one of our TAC engineers, visit

If anyone else in the forum has some advice, please reply to this thread.

Thank you for posting.

New Member

Re: Call Manager 3.1.2C - 6608 - Hum on PRI's

We have had a similar problem. The first time it was only happening on 3 of the 23 channels. We opened a TAC case and were told 1) to upgrade our loads to support patch B and 2) TAC thought it was a DSP hardware problem. So did I until it happend on a different port on a second 6608 later in the week. A reset does clear the problem. After the second time I impelemented the Support patch B-loads for the 6608. Keeping my fingers crossed. Did you have support patch B installed?

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