[asterisk-users] Digium Fax Driver

[Tilghman Lesher]

On Sunday 07 June 2009 19:39:50 Lee Howard wrote:
> Tilghman Lesher wrote:
> >> What's the use case for the Digium
> >> driver? Am I missing something by not using it?
> >
> > While they accomplish the same goal, the commercial driver is based upon
> > a different codebase,
>
> Ok.
>
> > provides support for patented fax protocols,
>
> Really?  V.34-fax (33,600 bps) is supported?  I had understood differently.

I would research the patents involved, but I am prohibited by employment
contract from exploring patents granted.  My understanding is that there are
certain aspects of fax that are still under patent, and those are provided
(along with indemnification) by the commercial driver.

> > and enjoys
> > far more testing than Steve can reasonably do for an unpaid side project
>
> I can't speak for how much testing the T.38 or T.30 sides to spandsp
> have had.  However, the T.31 and V.17, V.29, V.27ter, and V.21 aspects
> have undergone a *tremendous* amount of testing and development scrutiny
> (as these are used in IAXmodem).  I am aware of single installations
> that communicate successfully with very arbitrary kinds of fax machines
> in the USA which alone have communicated several millions of pages of
> fax in the last two years.  If there ever is a problem (and it is
> extremely rare) I hear about it.

And I agree that IAXmodem is by far more reliable than the builtin fax support
in spandsp.  I'm not suggesting that the commercial driver is more reliable,
only that it enjoys far more testing.  I don't know what part of my knowledge
is considered under NDA, so I'm hesitant to say more than that.

That said, hours of use in production do not speak to the amount of testing
done.  I myself have software that has been in production for millions of
hours (unrelated to Asterisk), and the amount of testing it enjoyed was less
than one hour.

> So I don't know of what kind of testing you speak, but I would caution
> you to reserve judgment simply on the basis that it is "an unpaid side
> project".

IAXmodem is a completely different ball of wax, and I think you would agree
that if the builtin FAX support in spandsp provided excellent support, there
never would have been a reason for IAXmodem to be developed.

-- 
Tilghman