Re: [hylafax-users] COMREC invalid response received PSTN <--> Asterisk <--> Hylafax

[Lee Howard <faxguy@xxxxxxxxxxxxxxxx>]

Joseph wrote:

> Can somebody point me in a right direction.
> I'm running Hylafax with Asterisk:
> PSTN <--> Asterisk <--> Hylafax
>
> I'm using an external "MultiTech Modem"
> Sending faxes works flawlessly, though receiving faxes works 90% of the
> time.
>  

You're going to have lots of trouble with this configuration because to 
accomplish this configuration you're either using a TDM card and 
connecting the modem to that, or you're connecting the modem to an ATA 
device (such as a Sipura SP-2000).  The TDM card drivers have known 
problems for faxing, and in using an ATA device you're converting the 
fax audio stream to a VoIP stream, and you can run into problems that way.

That said, I sometimes test HylaFAX with an analog modem connected to an 
ATA, and generally speaking it works tolerably well, but there are far 
more errors with it than if I were to plug the modem directly into a 
PSTN line.

Your best chance for success this way would be to use latest HylaFAX CVS 
HEAD and to switch to Class 1.

The other option with Asterisk, currently, to get reliable faxing is to 
ensure that the PSTN line is digital and that Asterisk never converts it 
to an analog signal.  So the PSTN line needs to be T1/E1 coming into 
Asterisk on a TE405P (for example), back out on another T1/E1 port, and 
then into another digital device, such as a T1 channel bank; then you 
plug the analog modems into that.

Someday, when Asterisk supports T.38 (and as T.38 employs T.30 protocol 
I must also say that when it supports T.38 as *reliably* as HylaFAX 
employs T.30), then you could plug your modem into an ATA that supports 
T.38 and use T.38 to avoid VoIP-streaming the fax audio signal.

Lee.


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