[Asterisk-Users] fax with asterisk

Thu Feb 17 11:43:39 MST 2005

Some of the issues I have had with fax with IP Centrex (my team was
responsible for an IP Centrex product at a CLEC) that sounds like you are
having, had to do with a number of factors:

- Network: latency, jitter, packetloss... fax is intolerant
- Gateways and IADs: echo cancellers incorrectly set and NSE incorrectly
set, attenuation on the PSTN side incorrectly set
- Fax type: G3 or superG3, the echo-can settings and NSE settings are
different for each since they are completely different ;-)

Some of the symptoms were:
- complete inability to send/receive faxes
- partial faxes (x pages received/sent out of x+y total)

I have never heard of a noise component though... which would account for
the scrambling you mentioned. The RTP wouldn't be modified in transit or the
packets checksum would barf. Its sounds like it maybe getting scrambled by a
terminal which in * case could be the transmit/receive fax machines or *
itself.

I hate fax over VoIP. E-fax anyone? :-)

> -----Original Message-----
> From: asterisk-users-bounces at lists.digium.com [mailto:asterisk-users-
> bounces at lists.digium.com] On Behalf Of Justin Richards
> Sent: Thursday, February 17, 2005 9:08 AM
> To: Keith Burns
> Cc: Asterisk Users Mailing List - Non-Commercial Discussion
> Subject: Re: [Asterisk-Users] fax with asterisk
> 
> I'm not using any Digium cards.  I'm actually using SpanDSP and
> app_rxfax to process incoming faxes.
> 
> After drilling into it for about 8 hours yesterday I come to realize
> that there is a lot more to it than the asterisk upgrade.
> 
> I patched my FC3 box, which means libtiff is now 3.6.1 which according
> to Steven (spandsp) is broken for this application.  First, i compiled
> the latest spandsp which didn't make a difference. I re-compiled the
> rxfax and txfax apps, got nowhere.  Finally started trying to revert
> to an older libtiff, but apparently went too far back (3.5.7) and
> ended up getting core dumps.  I am need to downgrade libtiff to 3.6.0,
> and everything dependant on libtiff to try again.  simply downgrading
> libtiff on its own doesn't work well.. :-(
> 
> Thats what I get for patching.. :-)  This setup worked nearly flawless
> until I upgraded, so I'm pretty sure I can get it back again after i
> downgrade the right stuff in the right order.  If anyone has that
> list, please share!!
> 
> 
> On Wed, 16 Feb 2005 19:45:51 -0700, Keith Burns
> <kburns at porchlightcom.com> wrote:
> > Are you both using Digium cards?
> >
> > Do you know if you are using G3 (standard) or SuperG3 (like a modem) fax
> > machines?
> >
> > > -----Original Message-----
> > > From: asterisk-users-bounces at lists.digium.com [mailto:asterisk-users-
> > > bounces at lists.digium.com] On Behalf Of Justin Richards
> > > Sent: Wednesday, February 16, 2005 4:25 PM
> > > To: Asterisk Users Mailing List - Non-Commercial Discussion
> > > Subject: Re: [Asterisk-Users] fax with asterisk
> > >
> > > I'm getting a lot of this too :-( my fax stuff worked great under 1.0
> > > but after upgrading to 1.0.5 i've been broken..
> > >
> > >
> > > Fax3Decode2D: Warning, (FakeInput): Premature EOL at scanline 496 (got
> > > 912, expected 1728).
> > > Fax3Decode2D: (FakeInput): Bad code word at scanline 497 (x 470).
> > > Fax3Decode2D: Warning, (FakeInput): Premature EOL at scanline 497 (got
> > > 470, expected 1728).
> > > Fax3Decode2D: Warning, (FakeInput): Line length mismatch at scanline
> > > 498 (got 3195, expected 1728).
> > > Fax3Decode2D: Warning, (FakeInput): Line length mismatch at scanline
> > > 500 (got 2471, expected 1728).
> > > Fax3Decode2D: (FakeInput): Bad code word at scanline 501 (x 1595).
> > > Fax3Decode2D: Warning, (FakeInput): Premature EOL at scanline 501 (got
> > > 1595, expected 1728).
> > > Fax3Decode2D: Warning, (FakeInput): Line length mismatch at scanline
> > > 503 (got 2583, expected 1728).
> > > Fax3Decode2D: Warning, (FakeInput): Line length mismatch at scanline
> > > 504 (got 1877, expected 1728).
> > > Fax3Decode2D: (FakeInput): Bad code word at scanline 506 (x 22).
> > > Fax3Decode2D: Warning, (FakeInput): Premature EOL at scanline 506 (got
> > > 22, expected 1728).
> > > Fax3Decode2D: Warning, (FakeInput): Line length mismatch at scanline
> > > 507 (got 1818, expected 1728).
> > > Fax3Decode2D: Warning, (FakeInput): Line length mismatch at scanline
> > > 509 (got 1729, expected 1728).
> > > Fax3Decode2D: Warning, (FakeInput): Line length mismatch at scanline
> > > 510 (got 1738, expected 1728).
> > > Fax3Decode2D: Warning, (FakeInput): Line length mismatch at scanline
> > > 511 (got 2228, expected 1728).
> > > Fax3Decode2D: Warning, (FakeInput): Line length mismatch at scanline
> > > 514 (got 1824, expected 1728).
> > > Fax3Decode2D: Warning, (FakeInput): Line length mismatch at scanline
> > > 515 (got 2466, expected 1728).
> > > Fax3Decode2D: Warning, (FakeInput): Line length mismatch at scanline
> > > 516 (got 1730, expected 1728).
> > > Fax3Decode2D: Warning, (FakeInput): Line length mismatch at scanline
> > > 517 (got 2534, expected 1728).
> > > Fax3Decode2D: Warning, (FakeInput): Line length mismatch at scanline
> > > 518 (got 1949, expected 1728).
> > > Fax3Decode2D: Warning, (FakeInput): Line length mismatch at scanline
> > > 519 (got 1830, expected 1728).
> > > Fax3Decode2D: Warning, (FakeInput): Line length mismatch at scanline
> > > 521 (got 3401, expected 1728).
> > > Fax3Decode2D: (FakeInput): Bad code word at scanline 522 (x 775).
> > > Fax3Decode2D: Warning, (FakeInput): Premature EOL at scanline 522 (got
> > > 775, expected 1728).
> > > Fax3Decode2D: Warning, (FakeInput): Line length mismatch at scanline
> > > 523 (got 2413, expected 1728).
> > > Fax3Decode2D: Warning, (FakeInput): Line length mismatch at scanline
> > > 524 (got 2279, expected 1728).
> > > Fax3Decode2D: Warning, (FakeInput): Line length mismatch at scanline
> > > 526 (got 2015, expected 1728).
> > > Fax3Decode2D: Warning, (FakeInput): Line length mismatch at scanline
> > > 530 (got 2677, expected 1728).
> > > Fax3Decode2D: (FakeInput): Bad code word at scanline 531 (x 1220).
> > > Fax3Decode2D: Warning, (FakeInput): Premature EOL at scanline 531 (got
> > > 1220, expected 1728).
> > > Fax3Decode2D: Warning, (FakeInput): Line length mismatch at scanline
> > > 532 (got 1729, expected 1728).
> > > Fax3Decode2D: (FakeInput): Bad code word at scanline 534 (x 0).
> > > Fax3Decode2D: Warning, (FakeInput): Premature EOL at scanline 534 (got
> > > 0, expected 1728).
> > > Fax3Decode2D: Warning, (FakeInput): Line length mismatch at scanline
> > > 536 (got 2454, expected 1728).
> > > Fax3Decode2D: Warning, (FakeInput): Premature EOL at scanline 537 (got
> > > 0, expected 1728).
> > > Page 4 of /var/spool/asterisk/fax//1108596104.3.tif:
> > > 538 rows received
> > > 0 total bad rows
> > > 0 max consecutive bad rows
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> Content preview:  I'm not using any Digium cards. I'm actually using
>   SpanDSP and app_rxfax to process incoming faxes. After drilling into
>   it for about 8 hours yesterday I come to realize that there is a lot
>   more to it than the asterisk upgrade. [...]
> 
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