Below you will find a universal modem string I created which should 
work with most modems so you can play multiplayer DOOM! This modem 
string has been used so far with Best Data, Zoom, Super and other modem
brands, even one's with V.42 bis compression and it hasn't failed.
Just insert this modem string into the first line of your modem.cfg file
in your doom directory:

AT &D2 &Q0\G0 &K0 S37=9 N0 %C\N1

This string automatically sets modem speed to 9600 (S37=9) and disables
protocol and compression. It places the two modems into direct mode.
Note that both people must use the exact same string and  the one
with the slower modem should call. (Just to make sure it connects 9600)
If it doesn't work the other should try calling. If this is unsuccesful 
change the:  %C\N1  to  %C\N0  for both modems. This puts the link into
normal mode instead of direct. If this modem string works for you please
leave mail for OliverZ007 on America OnLine or mailbox number 131920 on
Imagination. Include your modem brand and speed. If it doesn't work still
write and tell me where it got stuck and exactly what you did. Thanx.