[asterisk-users] SPA3k wired to PAP2 for echo testing

[Bob Chiodini]

I'm in the US and had bad echo problems with the SPA3K and the latest 
firmware. I was under the impression that the echo was due to my long 
cable run to the CO ~15000'. Changing the impedance (900 ohms) would 
help for a while, but after a few days the echo came back. If I rebooted 
the SPA3K the echo would go away for a while, but always came back. 
Assuming a software problem, I back-revved to an earlier F/W version. 
This seemed to help, but was not a cure. It did not pass muster with my 
wife. BTW: I did not experience echo on SIP calls through my ITSP or 
locally w/in my network.

I've seen some chatter about a Global option helping, but never tried 
it. I gave up and switched to a TDM11B. There was also some talk about 
having the earpiece volume up too high such that the phone's microphone 
picked up the sidetone and caused echo. I did have better results when 
the phone's volume was turned down, but I the SPA3k echo problem was 
never cured

Bob...

James Harper wrote:
> In my seemingly endless search for the cause of echo on my SPA3000, I
> wired it up in the following configuration:
>
> Analogue Handset <--> (FXS)SPA3000(FXO) <--> PAP2
>
> And set the Line1 dialplan on the SPA3k to '(<:@gw0>S0)' which means
> that as soon as I pick up the handset I get linked straight through to
> the PAP2, which gives me dialtone.
>
> Even in this configuration, with my impedance settings set to the
> Australian standard of 220+820||120nf, and the PSTN and PAP2 echo
> cancellers enabled (or not, and all combinations of) I get local echo as
> soon as I pick up the handset (I hear my voice bounced back to me).
> Surely this shouldn't be??? There is no hybrid involved at all!
>
> If anyone on this list with a SPA3k (that doesn't have any local echo
> problems on the PSTN port) and an ATA with a FXS port, could they please
> try the above setup and post the results (including SPA3k hardware and
> firmware versions, and the ATA used)? I wonder if there is a problem
> with some versions of the SPA3k where there is some sort of inbalance on
> the PSTN port that causes echo right there rather than further down the
> line?
>
> Thanks
>
> James
>
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