[cisco-voip] Echo on PSTN calls

[Jonathan Charles]

Echo is a function of the analog 2-wire to 4-wire conversion in the hybrid
transformer at the central office.

IOW, it doesn't happen on PRIs.

In all likelihood, the echo is actually coming from the other side...

However, check your T1 for slips, since you already have the echo cancellers
are maxed out...

You can also try this:

voice-card 1
 codec complexity medium ecan-extended

However, I don't think you can do that with a PRI already configured...

What are the input gain and output attenuation?



Jonathan

On Wed, Sep 3, 2008 at 4:07 PM, Brian Lehigh <brianl at sti.net> wrote:

> Hello all,
> We have a 2811 with a VWIC2-2MFT-T1/E1 running MGCP with two PRI to the
> PSTN.  The 2811 is running 12.4(13r)T. We're running Call Manager 6.1.2.
> Some end users are complaining of echo when placing calls to the PSTN.  All
> users have either 7941 or 7961 phones.  SW Echo cancellation is enabled on
> both PRI with a 64ms Echo Cancellation Coverage.  We have tweaked QoS, etc.
> and just can't seem to reduce it.
> Is there anything else we can do to suppress some of this echo, short of
> buying the hardware expansion module?
>
> Thanks,
>
> -Brian
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> cisco-voip at puck.nether.net
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>
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