[asterisk-users] still got ReceiveFax() problem, how to properly setup asterisk fax?

[Roi Stork]

Ok, Im putting back echo cancellation, since there's no change at all in
the fax receiving success rate.
I'd like to focus back to the original topic.

My incoming faxes end up usually as either timeout or hangup error:

timeout - is this supposed to happen in an E1 line? Can the timeout
threshold be changed?

hangup - currently more frequently encountered. I noticed in the console
that the remote channel hangup status 16 shows up in the middle of the fax
session. According to sangoma, this is a normal hangup but asterisk fax
detects this as error. I have already set it to use the e1 line clock
source.


On Friday, July 27, 2012, Kevin P. Fleming <kpfleming at digium.com> wrote:
> On 07/27/2012 09:53 AM, Eric Wieling wrote:
>
>> People seem to think that Asterisk won't disable the Echo Canceler when
a fax tone is detected.  Why they think that is a total mystery to me,.
>
> Asterisk doesn't do this, the echo canceller itself does (or DAHDI does,
in some cases). With modern ECs, as well, they don't even get disabled when
a CED tone (from the answering FAX endpoint) is heard, they instead just
turn off their non-linear processors, because it's been found through years
of experience that leaving 'most' of the EC still in place makes FAX calls
more reliable than if it was completely disabled.
>
> Since the OP has a Sangoma card with an Octasic hardware echo canceller
on it, he should just leave it alone and let it do its job :-) Turning it
off is probably making things worse.
>
> Sometimes I wish it was possible to selectively eradicate 'conventional
wisdom' from the world!
>
> --
> Kevin P. Fleming
> Digium, Inc. | Director of Software Technologies
> Jabber: kfleming at digium.com | SIP: kpfleming at digium.com | Skype: kpfleming
> 445 Jan Davis Drive NW - Huntsville, AL 35806 - USA
> Check us out at www.digium.com & www.asterisk.org
>
> --
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