[asterisk-users] FAX detection in chan_dahdi 1.8.15

[Olivier]

2012/8/31 Jeff LaCoursiere <jeff at sunfone.com>

> > -----Original Message-----
> > From: asterisk-users-bounces at lists.digium.com
> > [mailto:asterisk-users-bounces at lists.digium.com] On Behalf Of Jeff
> > LaCoursiere
> > Sent: Tuesday, August 28, 2012 3:24 PM
> > To: asterisk-users at lists.digium.com
> > Subject: [asterisk-users] FAX detection in chan_dahdi 1.8.15
> >
> > Hi,
> >
> > I recently replaced a site that was using 1.4.[mumble] with
> > hylafax/iaxmodem.  They have an RBS T1 and were using about half of
> their 50
> > DID numbers for "fax to email".  This all broke with the new system :(
> >
> > The original chan_dahdi.conf had no mention of "faxdetect", so I assume
> it
> > was operating with whatever is the default.  Off?
> >
> > The new box originally had "faxdetect=no", and I found that all my test
> > faxes failed with negotiation errors.  When I finally tried
> > "faxdetect=incoming" test faxes from another machine running hylafax went
> > through fine, and I thought I was done.
> >
> > The following week the customer reported that inbound faxes weren't
> working.
> > When I looked at the log, I saw lots of these:
> >
> > chan_dahdi.c:     -- Redirecting DAHDI/24-1 to fax extension
> >
> > Which in my FreePBX setup eventually goes to a "no service" message and
> > hangs up.  I've never defined a "fax" extension and don't really know
> what
> > that is about.  Turns out that any fax machine that calls ends up
> following
> > this path.  If my other hylafax server calls, it follows the normal path
> and
> > gets answered by my pool of iaxmodems. I don't really understand the
> > difference between the two types of calls, first of all.
> >
> > So it seems from this experience and a recent thread on -users that
> enabling
> > faxdetection in chan_dahdi sets up some additional buffering that at
> least
> > in my case, in 1.8, seems to be required (without it all inbound faxes
> fail
> > from my hylafax server with negotiation problems).
> > Unfortunately for me, this also seems to bypass normal DID handling and
> > sends calls to an undefined "fax extension".
> >
> > Can anyone shed some light?
> >
> > Thanks,
> >
> > j
> >
> > On Tue, 2012-08-28 at 15:28 -0500, Danny Nicholas wrote:
> > IIRC correctly this is sort of like the "s" extension; you set up your
> fax
> > handler in [default,fax,1].  Not sure how that is done in FreePBX.
> >
> >
>
> I've managed to hack a fix for this... in chan_dahdi.c I found two
> places where an "async goto" happens right after the message
> "Redirecting to fax extension".  I simply commented it out in both
> places.
>
> While looking a the source I noticed that an attempt is made to create a
> new channel variable "FAXEXTEN" with a comment "save the DID number
> before sending to the fax extension".  I created a "fax" context in
> extensions.conf and tried to use ${FAXEXTEN} to properly route my
> inbound fax to email calls, but it turns out that it is just set to "s",
> which isn't useful at all.  I spent some time trying to figure out where
> in the channel structure the actual DID information exists, as properly
> setting the "FAXEXTEN" variable is arguably the right "fix" for my
> problem.  But I'm just not familiar enough with the internals :( I'm
> surprised others haven't had this issue...
>
> Anyway commenting out the redirection did the trick for me.
>
> Cheers,
>
> j
>
>
Which Freepbx version are you using ?
Have you installed Freepbx's "Fax Configuration" module ?

Are you trying to attach fax-to-email service to incoming DIDs or to SIP
endpoints ?
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.digium.com/pipermail/asterisk-users/attachments/20120913/f009f8cf/attachment.htm>