Echo on PRI calls

Unanswered Question
Feb 5th, 2008

Users are occasionally experiencing echo on PSTN calls. The E1 ports are MGCP-controlled, and have echo cancel coverage set to 64ms (the default) and have 'echo-cancel erl worst-case 3' configured under each of the voice-ports.

Would increasing the ERL worst case to 6dB have any effect? The other option may be amend the input gain and output attenuation.

The DSPware is 4.4.24, IOS 12.4(13b).

I have this problem too.
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rob.huffman Tue, 02/05/2008 - 05:47

Hi Matthew,

I am going to suggest that you update the IOS which will also upgrade the DSP's. We were recently having some really bad intermittent Echo problems that were completely eliminated by going to IOS 12.4(15T1). I am pretty sure we were at 12.4(11) if my feeble mind can remember.

Just a thought,


mmelbourne Tue, 02/05/2008 - 06:19

Cheers mate. Many a weird issue has been solved with an IOS upgrade. We've upgraded once before, from 12.3(something)T to 12.4(13b) and thought the problem had gone away! What is the DSPware bundled with 12.4(15)T1?

Do you have anything special configured under your voice-ports for echo cancellation and/or signal gain/attenuation.

rob.huffman Tue, 02/05/2008 - 08:27

Hi Matthew,

You are most welcome my friend! The DSP version with 12.4(15)T1 is 9.4.0

We have no other configs for Echo cancellation etc. I have not had a single complaint since this upgrade and we used to have multiple complaints per week :)

Hope this helps!



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