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New Member

Troubleshooting echo

1751v Router w/2 2port DID VIC's

I'm attempting to troubleshoot the sporadic voice issues one of my remote offices are having, but I've read so many support docs that I?ve got myself confused. The most common issue reported is echo. The people on the IP side of the legs are hearing the echo, not the outside (analog).

My voice ports are setup as follows:

voice-port 1/0

input gain -3

echo-cancel coverage 48

no vad

no comfort-noise

timing dialout-delay 300

I've been reading through an impedance troubleshooting doc and I'm concerned about the ERL levels that are being reported.

I make a test call via a typical outside analog line to a DID number in that office. then, I issue a test tone sweep on that particular port and here's what I see:

A-1751#test voice port 1/1 inject-tone network sweep 200 0 0

Freq (hz), ERL (dB), TX Power (dBm), RX Power (dBm)

104 -79 -82 -3

304 -79 -82 -3

504 -79 -82 -3

704 -79 -82 -3

904 -79 -82 -3

1104 -79 -82 -3

1304 -79 -82 -3

1504 -79 -82 -3

1704 -79 -82 -3

1904 -79 -82 -3

2104 -79 -82 -3

2304 -79 -82 -3

2504 -79 -82 -3

2704 -79 -82 -3

2904 -79 -82 -3

3104 -79 -82 -3

3304 -79 -82 -3

3404 -79 -82 -3

Those ERL values aren't even close to what the troubleshooting docs recommend. I've tried all 5 impedance settings as well as changing the input gain, output attenuation, and the echo-coverage to try and eliminate the echo problems..

Do those ERL levels (-79) look normal to anyone?? Any advice on what I should do next to get to the bottom of this echo problem?

(Just realized I posted this in the wrong Topic, Sorry!)

New Member

Re: Troubleshooting echo

Can you tell me the IOS load and the DSPWARE version (Show Voice DSP?)


New Member

Re: Troubleshooting echo

IOS is 12.3(16) (there might be more to that but I renamed the bin before loading and I can't find the original)

DSP version: 4.1.41

New Member

Re: Troubleshooting echo

Check out this bug and let me know what you think.


New Member

Re: Troubleshooting echo

Thanks for the bug info, but our DSP version is 4.1.41 and the affected bug version is 4.4.13.

Do you guys think it's worth opening a TAC case to see if they can help me get that ERL level higher?

New Member

Re: Troubleshooting echo

Ya I guess so, sorry that I read your DSP version wrong, I was thinking yours was in the affected DSP version line.

New Member

Re: Troubleshooting echo

I've initiated the test tone from the 7960 and was able to replicate near or exactly the same erl that I have seen in other docs. I had to call from one 7960 to another 7960 via the pstn and once the call is established initiate the test tone from both phones.

Press the Settings button on the IP phone to enter the Settings menu in order to enable the tone


This enables the Tone softkey for as long as this phone is registered to Cisco CallManager.


Press **##**3 on the Cisco IP Phone 7940 or 7960 keypad while the phone is not on a call. When

you go to Option 5 "STATUS", you should see more debug information (for example, Stack

Statistics, and Debug Display).

Note: From Load #P0030301ESP5, you need to unlock the phone first, then you can press **##**3.

You need to be careful because if you press **#** consecutively, you reset the phone (because of

the **#** sequence).

This enables the Tone softkey for as long as this phone is registered to Cisco CallManager.


Place a call to the source phone with the echo problem.

Once the call is established, press the "i or ?" button twice. This brings up the statistics for the call.

Note: If the **##**3 key sequence works, you should have a Tone softkey available. Press the Tone

softkey and the phone begins to generate a 1004 Hz tone at -15 dB. The only way to stop the tone is

to end the call.

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