[cisco-voip] Echo on PSTN calls

[Jonathan Charles]

Um, no, it should be external (unless it is a PTP, then you set one side to
external, and the other to internal).

You need to do a network-clock-select t1 1 [interface of PRI]

Set it to first preference and the slips will go away... and set it to line
clocking.



Jonathan

On Thu, Sep 4, 2008 at 10:15 AM, Brian Lehigh <brianl at sti.net> wrote:

> Jonathan,Thank you for the reply.  Sure enough I have a bunch of slips on
> both T1's.  Clock was set to external on both so I'll try changing that
> first.
>
>
> -Brian
>
> On Sep 3, 2008, at 5:06 PM, Jonathan Charles wrote:
>
> 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
>> _______________________________________________
>> cisco-voip mailing list
>> cisco-voip at puck.nether.net
>> https://puck.nether.net/mailman/listinfo/cisco-voip
>>
>
>
>
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