[newbie] modem problems

[brian1151]

I am running Mandrake 6.0. I have tried repeatedly, but unsuccessfully to
get my modem working. My modem is on Com4 under Windows,  but I cannot
find it under Linux. I try to find it on /dev/ttyS3. I do get a modem
ready when I do a query, but there are no ATI commands. I have tried
changing the CR/LF, but that doesn't work either. What should I try next.
My modem is not a win modem.
                        Thanks