Re: flexfax: new modems vs Class 2

[Steve Williams <steve@genie96.com>]

[snip] 
> While we're on the subject of which modem to use, I'd like to hear about
> experiences with receiving faxes, which has always been a problem for us, 
> with both the MultiTech ZDX and Zoom Telephonics modems.  We can send faxes
> anywhere, even overseas where the phone lines are often inferior to 
> domestic connections.  But receiving faxes has always been dicey.
 
Hi,
We use the ZDX's here.  I have a post from quite a while ago that deals with
ZDX's receiving faxes.  Please see below, and good Luck,

	Steve Williams, Calgary, Alberta, Canada
	Genie Computer Systems Inc.
	steve@genie96.com
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>From daemon Thu Sep 19 11:00:43 1996
From: Glenn Burkhardt <glenn@aoi.ultranet.com>
To: flexfax@sgi.com
Subject: MultiTech ZDX2834 modems

I've been working with MultiTech support, and we've found out how to
improve the ZDX 2834's ability to receive faxes.  The receive threshold
in negative decibels is determined by the S38 register.  Its factory
default value is 43; changing it to 35 makes it possible to receive
faxes from our AT&T 3510D fax machine (and probably many others).  

The command "ATS38=35" will change the value of the S register.
The command "AT&F9" will prevent the factory default value from being
loaded should the command "AT&F" be issued.  So, recommend this
one-time, out of the box, initialization for the modem:

AT&F
ATS38=35
AT&F9
AT&W0

The explanation they had was that when carrier was dropped as part of the
normal facsimile handshaking, noise on the line was above the receive
threshold level, making the modem think that carrier hadn't be dropped.
Eventually, the T2 timer expired, and the modem reported "+FHNG:73"
(T.30 T2 timeout, expected page not received (code 73) ).  Increasing
the modem's receive threshold to -35db keeps the noise level below the 
carrier, at least for my fax machine and phone lines

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