flexfax: some little finding about USR Sportster

["Gary Ng (Winclient)" <garyn@winclient.com>]

As anyone on this list may know that USR
is notorious as a fax modem. I have played
around with this beast lately and think that
my experience with it may be helpful for
other 'must-be-USR' users (though I really
would like to advice people to stay away
from it).

USR Sportster supports Class 1 and 2.0 but
both has their own problems.

Class 1.

Sending seems to be pretty reliable except when
you are communicating at 14400 (v.17). In this case,
AT+F commands cannot be pumped to the modem
too fast (seems that a 10ms delay is good enough).

Receiving seems to be ok except when at 9600 (v.29).
If the other side is using a fax software with a fax modem
running as class 2, the AT+FRM session would terminate
pre-maturely returning around 2k of rubbish. I seen this in
a number of Rockwell based fax modem and the result
are almost repeatable.

Class 2.0
Sending is buggy but again depending on the receiving
fax machine or modems. It's +FDIS response may sometimes
give you some extra rubbish bytes without the OK and it can
be broken into 2 or more 'lines' instead of completely 'quoted'
with CRLF. To a number of other plain old fax machines, it just
disconnect immediately when connection has just been made.

Receiving seems to be ok and I found no special problem.

So just when one think that how about Class 1 for sending and
Class 2.0 for receiving ? Yes, it gives me pretty good result
(i.e. I see no problem so far). Unfortunately, for my X2 voice, it
will go into a state of total lock up which requires power reset.
Haven't tried on older models.

Hope this is helpful

Gary