[Asterisk-Users] Echo cancellation, when software doesn't cut it. Whats next?

[Robinson Tim-W10277]

All voip providers will use digital 4-wire interconnect to Asterisk or
similar, so echo problems are much reduced, as there are only 'echo
points' at the far end and your handset.

Using an analogue card will always have its issues if you have
significant propagation delay in the path anywhere.
You will see much bigger echo problems where the line is mismatched to
the analogue card. This will be in most places other than the US, as the
analogue cards only seem to support a 600 ohm line impedance.

If you want my recommendation, abandon analogue and get a basic rate
ISDN line and a zaphfc card.

Rgds
Tim
-----Original Message-----
From: asterisk-users-admin at lists.digium.com
[mailto:asterisk-users-admin at lists.digium.com] On Behalf Of Rich Adamson
Sent: 01 July 2004 14:21
To: asterisk-users at lists.digium.com
Subject: Re: [Asterisk-Users] Echo cancellation, when software doesn't
cut it. Whats next?


> Over the last couple weeks I've tried everything I could get my hands 
> on in an attempt to get rid of my echo problems. Using a CVS checkout 
> of just yesterday, I've tried every echo cancellation routine in 
> zconfig.h (including Mark2 w/Aggressive) , as well as the 
> echotraining=800 mentioned on this list just last week.
> 
> While some things worked better then others, I would consider none 
> acceptable solutions in my situation. Playing with rx/tx gain values 
> just seemed to quiet the voice down and along with that the echo 
> happened to be less noticeable. I could almost get the echo to 
> disappear with a low enough rx/tx gain, but then the voice could 
> barely be heard, or DTMF tones stopped working.
> 
> So whats the next step?
> 
> I only get echo when dialing over the PSTN. Using Nufone to dial a 
> PSTN number results in absolutely zero echo. Do I put in a request for

> a Telco technician to come out and take a look at the lines?
> 
> One page on the Wiki says:
> 
> "Most of the telco's have technicians with the equipment necessary to 
> help find the problem if the problem really is their outside plant. 
> However, getting to that person can be a real challenge."
> 
> Any suggestions on ways to overcome the challenge of getting the right

> technician on the phone?

Mike,

Contact me off list and let's see if we can isolate the issue. Can't
tell from the words you've used what steps you've gone through to date.

Rich


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