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No-way audio- VG200 Problem?


We are having random no-way audio problems with some of the phones (7960's mostly, no reports of other models) on our CM4.1 system. The problem creeps up every 5-7 days, and only appears to affect some of the phones.

Yesterday morning, I had two different buildings complain of the same problem- Incoming calls ring, but nobody is there and outgoing calls not ringing out. (When they called my cell, it rang, but they never heard the ringback tones.)

Yesterdays problem was only reported by two of nine buildings.

Resetting a phone doesn't change anything. If I reset the VG200, the problem goes away for another 5-7 days.

When I looked at the VG200 yesterday, there were only 4-6 calls in progress at the time.

The VG200 has been in service for nearly seven years, and no changes have been made recently. The last changes were to add dial-peer statements for new buildings that were brought online with IP phones.

The IOS version on the VG200 is 12.2(4)T1, it is configures as an H323 gateway in CallManager. Our CM is version 4.1(3)sr3b.

Does anyone have suggestsion on what to monitor or check to locate the source of the problem?

Hopefully I've given enough information to accurately describe the problem.


Steve Barr

Madison Local School District


Re: No-way audio- VG200 Problem?

I've seen so many times when no audio is caused by bad DSPs in the GW, especially with DSPs that terminate T1/E1 circuit.

I'm not familar with VG200. From what I remember VG200 only has 2 FXO ports. What's your PSTN connection?

New Member

Re: No-way audio- VG200 Problem?

I negelected to include how we are connected to the PSTN. In the VG200, we have a T1 VIC module, connected to an ISDN PRI.

We have no FXO ports in the VG200.

Is there something that I can monitor on the VG200 to see if bad DSPs are causing the problem?

If I look at the ethernet or T1 connections I see 0 errors of any kind.



Re: No-way audio- VG200 Problem?

First, do show logging to see if there are any errors pointing to DSP.

Show voice dsp is another good command. Look at TX/RX pack count. TX and RX counts should have similar values. If they differ by a lot, DSP issue is a suspect.

There are tons of IOS bugs related to DSP issues. You might want to check Bug Toolkit.

Again, the root cause might be something else. If this is happening regularly I highly recommend opening TAC case.

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