[cisco-voip] Phone echo

[Nick Matthews]

There was a real bad echo bug in the 12.4 train around 12.4(11)T and 12.4(7)
or so.

The trick is replicating the problem.  Sometimes you can use output gain and
attenuation to reduce the difference between the outgoing voice and the echo
coming back in so that the echo canceler can tell the difference between
voice and echo.

Like mentioned, headsets will get you.  So will latencies over 128ms.  G.114
(?) says 150ms, but in reality you really want to be less than 150 if a PSTN
gateway is involved because of this limitation.

I've got a particularly tricky bug out there that still isn't solved:
CSCtb26941

If you do a 'show call active voice echo summary' and you see the tail
jumping between 24ms and 112ms, you're hitting the bug.  A reload helps, or
you may try IOS in the 15.x train since some of the echo code has changed.
Otherwise you can reload the router and it probably won't happen to you
again unless you've got a lot of routers.  This thing can take up to 2-3
years to hit some times.

-nick

On Mon, Aug 23, 2010 at 4:52 PM, Marcus Smith <msmith at laurinburg.org> wrote:

>  The users are using handsets and these are external calls.  Also, this is
> what I got after using sh controllers t1command:
>
> 2811-Gateway#sh controller t1
> T1 0/0/0 is up.
>   Applique type is Channelized T1
>   Cablelength is long gain36 0db
>   No alarms detected.
>   alarm-trigger is not set
>   Soaking time: 3, Clearance time: 10
>   AIS State:Clear  LOS State:Clear  LOF State:Clear
>   Version info Firmware: 20060707, FPGA: 13, spm_count = 0
>   Framing is ESF, Line Code is B8ZS, Clock Source is Line.
>   CRC Threshold is 320. Reported from firmware  is 320.
>   Data in current interval (231 seconds elapsed):
>      0 Line Code Violations, 0 Path Code Violations
>      0 Slip Secs, 0 Fr Loss Secs, 0 Line Err Secs, 0 Degraded Mins
>      0 Errored Secs, 0 Bursty Err Secs, 0 Severely Err Secs, 0 Unavail Secs
>   Total Data (last 24 hours)
>      0 Line Code Violations, 0 Path Code Violations,
>      0 Slip Secs, 0 Fr Loss Secs, 0 Line Err Secs, 0 Degraded Mins,
>      0 Errored Secs, 0 Bursty Err Secs, 0 Severely Err Secs, 0 Unavail Secs
>
> Marcus Smith
> IT Manager/Dir
> City of Laurinburg
> Direct   (910) 291-2580
> Mobile  (910) 280-2781
> msmith at laurinburg.org
>
> ----- Original Message -----
> *From:* Marcus Smith <msmith at laurinburg.org>
> *To:* cisco-voip at puck.nether.net
> *Sent:* Monday, August 23, 2010 3:45 PM
> *Subject:* Phone echo
>
> Here is a little problem for all.  Over the last week or two, several users
> have stated that they are experiencing echoing( hearing their voices) when
> they are on the phone.  When I checked these extension I am hearing any
> echoing.  The users have been advised to verify whether or not these calls
> are from land line or cell phone.  They reported back both.   What other
> in-depth troubleshooting method can I apply
>
> Marcus Smith
> IT Manager/Dir
> City of Laurinburg
> Direct   (910) 291-2580
> Mobile  (910) 280-2781
> msmith at laurinburg.org
>
>
> _______________________________________________
> cisco-voip mailing list
> cisco-voip at puck.nether.net
> https://puck.nether.net/mailman/listinfo/cisco-voip
>
>
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