[robr]

Greetings, I've been trying to use an SPA-400 connected to Asterisk to fax via HylaFAX and IAXmodem. I wasn't having much luck, so I hired a HylaFAX guru to ssh in and take a look. The problem I was having was that the remote fax machine was picking up, but it wasn't connecting to my outgoing fax properly. I'm wondering if anyone has tried this with an SPA-400 before and encountered something similar. Below is an email I received tonight from the guru:

Rob,

I've tried just about every possible thing that I can think of and it's
amounted to nothing exept for more diagnostic information.

The problem appears to be either with your PSTN lines or with the
SPA-400 itself. The first noticeable problem is that it quiets the
audio volume considerably. I have to increase the gain by 15 dB (on the
Linksys) in order to get even partially adequate volume out of it. If I
increase the volume more than 15 dB then something quiets it back down
to nothing.

Still, increasing the gain only results in an acceptable amount of
volume. The resulting audio, however, is quite problematic itself.
This could, perhaps, be a result of network jitter between the Asterisk
box and the SPA-400, however, I'm more inclined to think that it's
coming from the same source as the volume dampening.

It should be unnecessary to adjust gains at all. Something else is not
right.

I use the Linksys SPA-2102 without any trouble (although I don't use the
FXO on it). However, the SPA-2102 does come with many more fax-specific
features that I'm not seeing on the SPA-400.

So at this point I'm not sure what else to do except to 1) check the
lines, or 2) test somehow without the Linksys involved... the results of
those tests would get us to a culprit, hopefully.

If you have a fax machine - plug it directly into those lines and send
faxes. If it works, then the lines are probably fine. If it doesn't
then the lines are probably at fault. My guess is that it will work
fine, and that the lines are just fine. [note - I've done this, lines are fine]

Now, I can't say much for Trixbox, because I don't know much about it,
but I've no doubt whatsoever that iaxmodem and HylaFAX are working
properly - and I also suspect that Asterisk is working properly. That
leaves us two things: the LAN and the SPA-400.

I don't think that we'd be seeing the kind of trouble that we're having
with just a LAN problem. Network jitter on LANs is much, much less
intrusive... generally.

That leaves us the SPA-400. Please note that nowhere in Linksys's
documentation on the SPA-400 does it state support for fax audio
pass-through... or even T.38 support such as the SPA-2102 has. So at
this point in time I would venture to guess that the problem in both the
volume dampening and also in the audio corruption is the fault of the
Linksys device.

I can appreciate not wanting to use the Asterisk voice mail system (or
even an internet gateway for the LAN). However, I think that a cleaner
setup would be to use a 4-port FXO Sangoma A200 card inside of the
Asterisk box - and do it all on the one system. Now, I know that you've
committed money and time to the Linksys SPA-400 setup - but unless we
can figure out what is going wrong, I would guess that you won't be able
to have fax with it involved in the call path.

Let me know how I can help further.


Thanks,

Lee.

[humba3]

This may sound dumb, but FAX is an inheritently analog service.. so why don't you connect Hylafax directly to your PSTN line instead of going via IP? Fax and IP has always, and will always be less than problem free. It can work quite well if properly set up, but eventually you'll encounter a remote fax that you just can't get to work no matter how hard you try.

[robr]

Originally Posted by humba3

This may sound dumb, but FAX is an inheritently analog service.. so why don't you connect Hylafax directly to your PSTN line instead of going via IP? Fax and IP has always, and will always be less than problem free. It can work quite well if properly set up, but eventually you'll encounter a remote fax that you just can't get to work no matter how hard you try.

The only VoIP here is the IAX connection between the HylaFAX and Asterisk, they reside on the same machine and Asterisk and the Sipura. The Sipura is connected to the same switch as the Asterisk box and the network has virtually zero traffic. There should not be a VoIP issue with this setup and VoIP is not the cause of low line volume. The problem is the SPA-400. As noted in the previous post, faxing over an SPA-2102 works fine (without FXO even).

I wanted to keep all our phone lines managed by the Asterisk (and be able to share them for voice and fax), but since Asterisk is running in a VM, a PCI card in that box was not an option, so I'm doing what you suggest. I'm moving HylaFAX to a dedicated box with a Mainpine Rockforce Quatro+ ($850 for a dedicated fax card vs. $250 for the SPA-400 which I was hoping would be multifunction). Not my first choice, but at least I know that setup will work.