[Asterisk-Users] SIP UA Fax device

[Simon Woodhead]

Hi Dan,

If you find one please let me know although we've had no success looking for
such a thing ourselves. Our experience to date in looking might be of some
use to you though...

We're trying to replace BRI lines with a H.323 connection to a telco over
our leased line. Faxes remain one of the problem areas. Logic says that
since faxes and modem were designed to send data over existing analogue
voice channels that it should be possible to send them over VoIP channels
but searching the archives for this list and elsewhere suggests otherwise.
Apparently because the data is being modulated and then demodulated
repeatedly through the various layers and VoIP is lossy it won't work. The
solution seems to be T.38 fax relay although asterisk doesn't support it.

We're playing with Hylafax (www.hylafax.org), an open source fax server. You
might get lucky asking around there for SIP support but to my knowledge it
only supports hardware modems. For us, we're looking at setting up asterisk
extensions on a TDM-400P and then looping a physical wire into fax modems on
a neighbouring machine. We've tested this with * dialling out and answering
existing ISDN channels and forwarding to/from a normal fax machine and it
works perfectly.

IP wise, as I mentioned, we want to ditch the ISDN and use our H.323
connection. We have two *s in different countries talking to each other by
IAX. Despite what the archives say, we have been able to send faxes from
analogue fax machines connected at each end (or dialling in/out to one end)
over a voice channel in between with no problems at all. We haven't tried
over the H.323. yet but will be doing so shortly.

I don't know which side of * you need the SIP connection but what works over
the net shouldn't struggle on a LAN. On the basis of our limited experience
so far, IP to outside seems to work fine and LANside you can either
physically connect a fax modem to * or hook up something like an ATA186 to a
fax machine/fax-modem.

I hope this is of some help and look forward to hearing how you get on.

Cheers,
Simon

----- Original Message ----- 
From: "Dan" <dtoma at fx.ro>
To: <asterisk-users at lists.digium.com>
Sent: Thursday, May 22, 2003 9:10 AM
Subject: [Asterisk-Users] SIP UA Fax device


> Hi,
>
> Anyone knows a software fax device which can act as a SIP UA?
> I want to have a SIP based FAX machine (sofware) on a PC associated with
an
> Asterisk extension.
>
> Thanks,
> Dan
>
>
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