🚀 go-pugleaf

I wrote a little fax-program (DOS, class 2/2.0, USR Sportster VI) and
I have only the following little problem:

The first view lines are correctly transmitted but then i get the
error message "unrecognized transparent data command" from the called
fax and the connection gets interrupted. I think the bug seems to be
in the handshake between program/modem or modem/"called fax".

If I query the Modem about RTS/CTS, DTR/DSR or XON/XOFF it always
returns that it IS ready to send. But as fast as i send the g3-data
the dialed fax cannot be able to receive it.
Theoratically it should work with HW-Handshake?!? Isn't there a
problem with SW-Handshake, because in the G3-fax page could be
XON/XOFF as data?

I send with max. 19200 bps and I tried various modem-settings.

What did i do wrong?!? "mgetty+sendfax" are unfortunately only for
Linux and working with the ports and modem works different in Linux
than in DOS.

Maybe somebody can help me, please
ERICH