[asterisk-users] Echo...

[Wireless]

(applogies for the layout, having to use outlook)



If I could crack the Echo problem then the VOIP PBX would pass the rigorous
wife test (WT).  I've used the TDM400P card and reduced the echo on one of
my 2 BT lines (the other one seems much better, but not perfect) to a point
where I can live with it but it not passing WT.  Lighting killed the FXO
modules in the TDM400P so I desided to go with the Sangoma A200, without
hardware echo cancel, this card is built like a brick sh*t house in
comparison with the Diguim one but I cannot reduce the echo any more that I
could before :( . If I use the aggressive echo canceller in Zaptel I can
kill the echo but find that I'm also losing the ends of words too... is
there a half way house?



Gordon, if you can afford it go for a Sangoma A200 with hardware echo
cancellation built in (it is my next step), the Sangoma support is
excellent. I had a problem with CLID so I let Sangoma SSH into my Trixbox
and they confirmed that  my config was fine and suggested adjusting the
gain - which fixed my intermittent CLID.



Good Luck



Harvey



----- Original Message ----- 
From: "Gordon Henderson" <gordon+asterisk at drogon.net>
To: "Asterisk Users Mailing List - Non-Commercial Discussion"
<asterisk-users at lists.digium.com>
Sent: Friday, January 12, 2007 10:16 AM
Subject: RE: [asterisk-users] Echo...


On Thu, 11 Jan 2007, Ken Williams wrote:

> I've never understood why people would think it's a PSTN issue.  I'm
> sure 99.999999% of Asterisk users are using Asterisk on lines they've
> had regular phone lines hooked up to before moving to Asterisk.  In my
> case I've also tried having the server plugged in to two systems that
> are 200 miles apart from each other serviced by different telco's, both
> lines previously being used for years without issue.
>
> I'm using Grandstream GPX-2000.  It works fine for VoIP calls both on
> the local net, and between locations across the net.  It works fine for
> outgoing calls, it's only on incoming calls that echo becomes an issue.
> I did some brief searching on this phone with echo issues, but most
> things I found were 2-3 years old and people had said firmware updates
> had fixed their issues.  I've had the phones for 2 months and updated
> firmware then, so I didn't think it'd be the phone, but if it is would
> love suggestions.
>
> I've read a ton on echo, love to read more, appreciate the link Leo,
> thanks for anything else you can offer.

I can't offer any more on this, but I have one installation where one of
the 2 incoming lines has echo. I went through pretty much the same as you
- upgraded, recompiled, run fxotune (which now produces some nmbers other
than zeros) but theres still an echo on it.

The echo moves with the line - the TDM400P card has 3 FXO ports - 2 are
PSTN one goes to a GSM adapter and the echo definately moves with the line
when I try it in each of the 3 FXO ports.

Even though I'm 99.99% sure it's a line problem I'm gonig to replace the
TDM card and modules next week.

I'm using GPX-2000 phones too FWIW, but I have many installations and it's
just this one that has the issues. This particular site only has 3 phones,
bu I still get it when I connect into it via an IAX trunk and dial out.

I've completely replaced the internal wiring from BTs DP in the building
to the PBX too and that didn't help. (Although in the process I managed to
wire someone elses phone into it and thought "Hurrah! echo gone" until I
called the number and it didn't ring - Doh!)

What's infuriating is that if I plug an ordinary el-cheapo £1.99 analogue
phone into the line it works perfectly.... HOWEVER ... if I have the phone
plugged in and the PBX pluged in then I can hear echo on the analog phone.

So I'm sure that after I change the card next week I'll still have echo,
but then I'll have to persuade BT to investigate the problem and how I'm
going to do that is going to be an intersting challenge!

My suspiction is that BT have used 2 wires from different pairs to bring
the line in from the street cab, or something along those lines. (although
the incoming pair in the DP looked OK to me)

So things to look for is the output of dmesg at boot time - make sure the
card is setup for your country - heres an example from one of my units:

Freshmaker version: 73
Freshmaker passed register test
Module 0: Installed -- AUTO FXS/DPO
Module 1: Not installed
Module 2: Installed -- AUTO FXO (UK mode)
Module 3: Installed -- AUTO FXO (UK mode)
Found a Wildcard TDM: Wildcard TDM400P REV I (3 modules)
Registered tone zone 4 (United Kingdom)


You'll get version numbers a bit further up:

Zapata Telephony Interface Registered on major 196
Zaptel Version: 1.2.12 Echo Canceller: MG2 (aggressive)

And the only other advice I can offer at this stage is: Good luck!

Gordon
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