[cisco-voip] Echo on IP Phone with PRI (CME)

[Tim Jackson]

Not sure if they use the same Flex DSPs as IAD2400 and the AS5xxx, but there
was a lot of bugs in the echo cancelers in the earlier loads..  I'd check
with TAC on that... We've had issues with a lot of the FlexDSPs and echo
problems...

I know the newest 12.4(4)T has this resolved...

You can also fix this with a separate DSP load in the flash when you boot
up...

--
Tim

On 6/2/07, Jason Aarons (US) <jason.aarons at us.didata.com> wrote:
>
> In the past the problem is typically the phone device load, handset
> volume level, or the DSP/IOS version, not a 2-wire to 4-wire conversion
> as CCO might lead you to believe...
>
> Input gain/output attenuation apply to PRIs, 7940/7960 phones have a
> tone generator built in and you can measure Echo Return Loss (ERL) to
> adjust the gain/attenuation.
>
> I would open a TAC case and check the IOS/DSP firmware version first,
> there have been a lot of bugs overall.
>
> You can request your telco bring out a T-Berd or similar test tool and
> prove there is no echo at the Smartjack eliminating them.
>
> -----Original Message-----
> From: cisco-voip-bounces at puck.nether.net
> [mailto:cisco-voip-bounces at puck.nether.net] On Behalf Of Linsemier,
> Matthew
> Sent: Saturday, June 02, 2007 12:43 PM
> To: Erick Bergquist; ciscovoip
> Subject: Re: [cisco-voip] Echo on IP Phone with PRI (CME)
>
> In the past any time I had issues with echo such as you describe here,
> it was handled by adjusting the echo cancel coverage parameters.  From
> what I understand, input gain and output attenuation commands have no
> effect on a PRI circuit because it's digital (and those commands are for
> analog POTS lines).
>
> I would suspect you are running into an IOS bug, a DSP resource that is
> intermittently failing, or receiving echo outside of the maximum
> coverage area or a telco side issue.  I would start with IOS and work up
> the list from there.  You may also want to verify if the echo is lasting
> the whole conversation, or just the first few seconds.  Remember that
> sometimes it takes a second for the echo cancel coverage to kick in and
> it can be noticable to the humar ear.  It's gotten much better since
> 12.4 was released.
>
> Matt
>
> ________________________________
>
> From: cisco-voip-bounces at puck.nether.net on behalf of Erick Bergquist
> Sent: Fri 6/1/2007 11:47 AM
> To: ciscovoip
> Subject: [cisco-voip] Echo on IP Phone with PRI (CME)
>
>
>
> Hi,
>
>
>
> I am having issue where users report echo on the IP phones
> every now and then that lasts the whole call. The echo they hear is
> their voice back on the IP Phone. The outside party does not hear echo.
>
>
>
> The T1 PRI controller is clean, no errors and the router
> network-clock is set to use the PRI.
>
> CME is on a 2811 with IOS 12.4(6)XE2
> , c2800nm-ipvoicek9-mz.124-6.XE2.bin
>
>
> Have tried different echo cancel coverage settings and input/output gain
> adjustments. They had no echo for almost a week then had it frequently
> for 1-2 days and now it is good again for past 2 days.
>
> voice-port 0/0/0:23
>
> input gain -3
>
> output attenuation 3
>
> music-threshold -45
>
>
>
> The phones are 7941s and firmware 8.0(4)SR2 -- is it safe to try latest
> firmware version on CME without IOS update?
>
>
> Any ideas?
>
>
>
>
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