isdn4linux and fax

Sven Liessem (liesse@misadm.tls.mms.fr)
Thu, 4 Dec 1997 19:09:38 +0100


> > I've just read the faq for i4l and it's stated that it does
> > NOT support fax (which was already said here by Gert some days ago).
> > On the other hand i4l emulates a serial port (ttyIxx) that can
> > be used to login with mgetty and at least some isdn cards out there
> > (USR Imodem and maybe others) support fax class 2.
> 
> Those modems have DSP hardware on board that does the fax protocol
> handling.

Ok that seems clear to me, something has to do the dirty job.

> > So now I'm wondering where the problem is. Is there really no way
> > to have fax on internal isdn cards ???
> 
> No. Unless you have really fast CPU, starve the rest of the system,
> and invest *LOTS* of time in programming the stuff.

Well that's the point that is VERY strange, at least for me. I understand
these arguments when we're talking about class 1 support because the
software must do everyting. Fax class 2 seems to boil down (sorry if
this is VERY simplistic) to a couple of AT commands followed by a data
flow including some special sequences (end of line, page and so on).

As the DSP does the protocol handling, if the card reacts like an analog
class 2 modem when you use it through ttyIxx, which seems to be the case for
the USR which claims to be a Courier, what else do you have to program ?
All just should work fine with a standard mgetty and sendfax.

Sven

--
Sven LIESSEM     Email : x_liesse@misadm.tls.mms.fr
HP-UX System Engineer   Phone : (33) 5 6219.6713
Steria Infogerance et Services  Fax : (33) 5 6219.7900
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