[Asterisk-Users] Re: Asterisk in production as a fax server, anyone?

[Adolfo R. Brandes]

Lee Howard wrote:
> However, based on the comments you give I'd suspect that you're having 
> what people seem to be calling "frame slipping".  There seem to be some 
> motherboards that react poorly with Zap cards (or their respective 
> drivers) and cause that.  Your zttest results should be revealing here.

	We hadn't thought of using zttest.  I'll do some research on how it can 
be used to detect frame slips and problems of the sort, and will post 
our results later.  Great pointer, though!

> The concurrent calls really isn't that big of a deal, either, if 
> those are your thoughts.  The bigger issue seems to be the quality of 
> the audio as it is delivered to the fax application/modem.

	Interesting.  The little information I've found on the subject seemed 
to imply that Asterisk couldn't handle more than a handful of fax calls 
using software DSP.  This could also be explained away by frame slips 
too, right?

> In my experience Sangoma offers better (or maybe just more caring) 
> post-sale support than does Digium, however, the "frame slipping" issue 
> seems to happen with both sets of hardware.

	Thanks for clearing that up.  I had begun to get the impression that 
Sangoma cards were overall better cards than Digium's.  It seems that's 
not necessarily the case.

> As for Eicon Divas being used for IVR, I've never used them 
> that way.

	We haven't, either.  It had just come to our attention, however, that 
using hardware DSP might be a better bet.  Nevertheless, little research 
was done with respect to using Eicon Divas as something similar to a Zap 
device with Asterisk.  It seems chan_capi might do the trick.
	
> The most success I've seen has been to bridge the call through Asterisk 
> to a T1 fax modem such as a Patton 2977 or an Eicon Diva Server with 
> HylaFAX running the modems.

	Now THAT is a very good idea!  To us, it means that if push comes to 
shove, there is a certain method for having IVR and reliable faxing 
available during a single call.  Thank you!  But just to make it clear, 
woudn't frame slips enter the picture here too?

	In any case, thank you for replying, Lee!  Your post was extremely helpful.

	Adolfo R. Brandes