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6608 and echo

A few users complained they have echo whem calls to PSTN. I noticed that Echo TailLength of the 6608 PRI on the CCM is 32ms, actually the maxium is 64.I think change this may fix the problem. But is there any disadvange to change the default to 64? Thanks

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Re: 6608 and echo

Hi -

Not sure about the taillength question but there is a document about 6608 and echo, URL below...



Re: 6608 and echo

Under older 6608 code, the above URL showed the only tools you had on 6608 to help eliminate echo. Under newer code with CallManager 3.3(3)SR2 (I think) and above, Cisco has integrated the same DSP code that's used on IOS routers to eliminate echo (sometimes referred to as Echo Beach). You can tell if your CallManager version came with the newer code if 64ms is available as the max echo tail length as opposed to 32ms.

With the new echo cancellation code, convergence is fast enough that there is no real downside to setting the ECAN tail length to the max and leaving it there.

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Re: 6608 and echo

Supposedly, higher echo canceller taillengths cause longer training times, meaning the echo heard on the first few seconds of a call that the echo canceller cannot cancel would last longer. Although I have recently heard from Cisco that the latest algorymths get around this and that there is no longer any reason to not max out the taillength number.

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