[Asterisk-Users] I hate to do this but..

[Jason A. Pattie]

Anton L. Kapela wrote:

>Jeremy McNamara said:
>
>  
>
>>Flebay it and use the proceeds to support Digium by purchasing Zaptel
>>hardware.  http://www.digium.com/
>>    
>>
>
>I like the zaptel cards, I really do. The price per port is better
>than other fxo/fxs's in almost all cases and the support I've received
>from Digium is second to none. However, deploying several pbx's for
>friends (and using the X100p's), I've come to find that the echo
>cancellation to be sub-par when contrasted with other makers. I
>realize ecan is a huge and complex issue, but it's central to really
>convincing me to 'buy' more Digium hardware.
>
>Such is the catch-22; it seems we need people to buy/support Digium in
>hopes that they can improve things overall -- hoping this includes
>work on dsp.c to achieve better ecan. It's difficult to recommend that
>someone buy 4 or 6 ports of fxo knowing that they'll probably be
>complaining to me about excessive echo.
>
>Note: I've tried every possible echo suppressor listed in the
>Makefile, and so far Mark2 + aggressive suppression works best, at the
>sacrifice of FDX. I'd like FDX and aggressive ecan. <G> This isn't a
>jab at zaptel or Mark, this note is to highlite one issue I've had
>recommending Digium hardware.
>  
>
I have this exact same problem as well.  We have a scenario in which we 
are not using any analog extensions, just SIP and IAX software based 
phones (DIAX, X-Lite, gnophone, (trying to use) linphone, etc.) with a 
single incoming POTS line to an X101P card.  First, the audio level 
coming from/to the X101P card is unacceptable, unless rxgain/txgain are 
turned up.  It starts becoming usable around 6.0.  The desired audio 
level is reached when the gains are increased to between 10.0 and 13.0.  
At 13.0, though, the sound becomes almost too distorted to be of use, 
but it is at a very acceptable loudness level.

As far as echo is concerned, there don't seem to be any problems on the 
side of the person calling into the system to the X101P card.  However, 
if they connect to a SIP/IAX extension, or the SIP/IAX extension makes 
an outgoing call through the X101P card, the echo on the SIP/IAX 
extension is horrendous.  Of all the echo suppressors I've tried, MARK3 
works the best for not blowing your eardrums out.  The problem is 
excrutiating when using MARK2 with AGGRESSIVE cancellation.  When this 
is enabled, and the rx/txgains are anywhere above 0.0 (even 0.5), the 
SIP/IAX client receives some sort of feedback or distortion that can 
only be described as an extremely loud screech or squelch that hurts 
very much.  And, it is rather explosive in nature.  It is partly solved 
by turning down the microphone volume and gain on the SIP/IAX client, 
but it does not stop the problem.  If the rx/txgains are set to 0.0, 
then the volume level coming from/through? the X101P is so low, that 
even turning the volume up all the way on the SIP/IAX client, it is 
extremely difficult to make out what the other party is saying (there is 
a bit of ambient sound level in the location we are working from, 
though).  The same happens if voicemail is left using the X101P.  
However, if voicemail is left using the SIP/IAX client, volume levels 
are very acceptable.

I don't understand what is going wrong.  Do I have a bad X101P card?  
I've tried this card in 3 different machines, so far.  I will be trying 
it in a fourth shortly and let you know how it goes.

Thanks.


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