[Asterisk-Users] External fax modem takeover of fxo?

[Walt Reed]

On Tue, Jan 18, 2005 at 09:40:47AM -0800, Lee Howard said:
> On 2005.01.18 08:36 Walt Reed wrote:
> 
> >I'm thinking of hooking up the faxmodem to the line directly, then
> >hooking the X100P to the modem's Phone port.
> 
> From what I've been able to determine, Asterisk would be most unhappy 
> if you did that.  On X100Ps that "phone" jack/port needs to simply be 
> ignored.  I have a telephone connected to mine, but it's only there in 
> the off-chance of an emergency, power outage, or to troubleshoot 
> problems with the FXO.

I understand that. That's not what I am thinking of. I want the plug the
modem in the the PSTN, and the X100P into the modem's Phone jack - NOT
plug the modem into the X100P Phone jack. When my hypothetical
"System()" call runs, the modem would pick up the phone and in the
process disable the phone port on the fax modem which should throw a
red-alarm on the X100P. When the fax is done, the fax modem would hangup
and reconnect the X100P to the PSTN.
 
> >Can I enable fax detection and use the fax extension to spawn an
> >external
> >command (halafax) to receive the fax?
> 
> Uh, well, in the obvious way yes, but not in the way that you seem to 
> be wanting to hear.
> 
> exten => s,1,Answer
> exten => s,2,wait(5)
> exten => s,3,....
> exten => fax,1,Dial(FXS_PORT)
> 
> Where "FXS_PORT" is an FXS port where a HylaFAX-controlled modem is 
> connected... or any other fax device for that matter.
> 
> The problem is, though, that there seems to be a significant amount of 
> data loss when receiving with this configuration... even using ULAW.  
> Now, an ECM-aware fax device may compensate well-enough, but there's 
> still a problem.

Yep - I read about all those problems. I have heard very few sucess
stories of running fax through * at all, which is why I was trying to
find a way to avoid it.

If I can get * to do the fax detection only and then kick off the
external process that should be enough...
 
> >What is the state of fax detection with the stable branch of * on an
> >X100P? Does it work reliably?
> 
> Fax detection is generally okay, but there are some problems.  See:
> 
>   http://bugs.digium.com/bug_view_page.php?bug_id=0002165

Hmm. Interesting. So the problem is that Fax detection doesn't work, so
the reporter goes through all the hoops and captures audio showing an
exact case where detection is failing and therefore the bug is closed.
He adds additional detail and the bug is closed AGAIN.

Cute. 

So the real answer is that * can't handle fax correctly and reliably at
all, so get a dedicated PSTN line... Is it just me or is the fact that *
can't do what a $70 fax machine can do seem a little bizzare?