[Asterisk-Users] Asterisk mangling faxes

[Jim Sneeringer]

All the fax modems I have seen do send CNG tones, but I have seen some very
old standalone fax machines that do not. They used to be quite common, but
in the last few years I have only seen one fax machine that does not support
CNG.

One workaround is to send the call to the fax machine on a timeout. Then a
fax that does not send a CNG can sometimes still get through.

-----Original Message-----
From: asterisk-users-admin at lists.digium.com
[mailto:asterisk-users-admin at lists.digium.com] On Behalf Of Eric Wieling
Sent: Wednesday, March 10, 2004 12:14 PM
To: asterisk-users at lists.digium.com
Subject: RE: [Asterisk-Users] Asterisk mangling faxes

First of all Asterisk does not support ${VARIABLES} as part of the
extension number.  i.e. exten => ${BLAH},1,NoOp is not valid, but exten
=> 1234,1,NoOp(${BLAH}) is valid.

Also Asterisk NEEDS the sending fax machine to send standard fax machine
tones (CNG, I think) for it to be detected.  When you send a fax the fax
machine starts sending tones as soon as the call is dialed.  Asterisk
listens for these tones and if it hears them it will route the call to
exten => fax,1,Blah if such an extension exists.

As I understand it some (many?) fax modems do not send the required tone
when making a fax call.

On Wed, 2004-03-10 at 10:47, Jim Sneeringer wrote:
> I'm having the same symptoms using X100P's, TDM400P's and WinFax, and have
> and have had no luck correcting it. I don't have a standalone fax machine
to
> test with.
> 
> Does anyone know if this a problem whenever faxes are sent and received
with
> a modem, or is it specifically WinFax? Is there any other way to
accomplish
> the goal of computer faxing with Asterisk?
> 
> Jim
> 
> -----Original Message-----
> From: asterisk-users-admin at lists.digium.com
> [mailto:asterisk-users-admin at lists.digium.com] On Behalf Of Bisker, Scott
> (7805)
> Sent: Wednesday, March 10, 2004 8:50 AM
> To: asterisk-users at lists.digium.com
> Subject: RE: [Asterisk-Users] Asterisk mangling faxes
> 
> Michiel,
> 
> Are you using WinFax? or one of the Products Based on Winfax?  I've seen
> this on all of our WinFax Stations, but none of our standalone Fax
machines.
> 
> -sb
> 
> 
> -----Original Message-----
> From: asterisk-users-admin at lists.digium.com
> [mailto:asterisk-users-admin at lists.digium.com]On Behalf Of michiel betel
> Sent: Wednesday, March 10, 2004 9:40 AM
> To: asterisk-users at lists.digium.com
> Subject: [Asterisk-Users] Asterisk mangling faxes
> 
> 
> Hi list,
> 
> Faxes come in over an E1 line  (on an TE410P) here and then are sent to 
> an analog fax machine attached to a T1 (also on the TE410P) & 
> channelbank (CAC1).
> Problem is that almost all faxes we send out and receive are mangled... 
> either only halve pages or very stretched text etc.
> Setup in extensions.conf is just:
> 
> exten => ${NN_FAX},1,Answer
> exten => ${NN_FAX},2,Dial(Zap/49,80)
> exten => ${NN_FAX},3,Hangup
> 
> echocancel is off for Zap/49 since the path is TDM only....
> 
> Any pointers to where to look??
> 
> Thanks, Michiel
> 
> 
> 
> 
> 
> 
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-- 
For Asterisk PBX related documentation go to
http://www.digium.com/index.php?menu=documentation and look at the
"Unofficial Links" section also see
http://www.voip-info.org/wiki-Asterisk also see my site at
http://www.fnords.org/~eric/asterisk/

BTEL Consulting

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