Re: [hylafax-users] Numerous NO CARRIER errors

["Siri Vias Khalsa" <sirivias.khalsa@xxxxxxxxxx>]

The "NO CARRIER" error is returned by the modem. It is waiting for a
dial tone and cannot hear one. You can look at the manual for your
modem, there is usually a way to specify an initialization string or
dial string that tells the modem not to wait for a dial tone.

It would be helpful for both "NO CARRIER" and "NO ANSWER" issues to
listen to the phone line while the call is happening (or turning up the
volume on the modem) to hear what is actually going on.

Also, I doubt you have 5 different modems that would work optimally with
the same configuration; each modem chipset can be different, you should
find the best configuration for each.

-Siri Vias

-----Original Message-----
From: hylafax-users-bounce@xxxxxxxxxxx
[mailto:hylafax-users-bounce@xxxxxxxxxxx] On Behalf Of Ryan Cooley
Sent: Wednesday, April 07, 2010 9:54 AM
To: hylafax-users@xxxxxxxxxxx
Subject: [hylafax-users] Numerous NO CARRIER errors

We've been having a problem with Hylafax for quite some time.  I'd say
1/3rd of our attempts to send faxes result in either NO CARRIER or NO
ANSWER errors.  

I've tried all the testing and tweaking I could think of.
Hardware/software flow control.  Changing baud rate, etc., etc.  I've
done plenty of searching of the web and mailing lists, and haven't found
anything remotely similar...  The few who report NO CARRIER errors seem
the have a simple solution.

We're using on-board and add-in serial port cards, with 5 different
modems, mostly various USR, but an old generic 14.4 as well, with no
difference in behavior between them.  All configured exactly the same.
This problem is prevalent on all modems tried.  

I've fully tested the modems and serial ports, and they appear to behave
perfectly 100% of the time no matter how much I try to stress them (at
least with normal PC data connections).  The relevant phone lines also
haven't demonstrated any problems at all in my testing.  

At this point, my suspicion is either a bad Hylafax binary, or bad modem
initialization/reset strings, but lacking a serial port sniffer, I'm not
even sure how to debug this further.  Changing either would be just
fine, if there's some reason for it more concrete than my guessing at
the causes.  I'm hoping this is a known problem that someone else has
seen.  If not, some direction on debugging further would be most
appreciated.

Software is RPM of hylafax-4.3.3-1rhel4 on CentOS 5.0

Log is attached for one example of such problems.  I've got hundreds,
but they all look exactly the same, just a different number, job ID, and
alternating between NO CARRIER and NO ANSWER.


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