You need to install martian driver kit. You will need kernel source necessary for compiling modem drivers installed. Go to linmodems through link provided below, there is a highlighted link in the first sentence to access archives of past cases if you need to read up, but on that same page is another link called scanModem, click it and read how to use it, click it's link on that second page to download it. Issue commands from the directory you put it in:
gunzip scanModem.gz
chmod a+x scanModem
./scanModem
A folder in that directory will show up called "Modem", inside is allot of info, the Ltmodem.txt (If this is Lucent Win Modem) will give you a link to driver source, instructions are in a README after unpacking it. If you need help, there will also be a file called "Modemdata.txt" I believe this is the one with a link to maintainers with the most experience in this field.
If this is a Lucent Win Modem on a 64 bit system, the martian_modem will need to be built in a 32 bit environment using ltmdmobj.o-8.31-gcc4.gz available on same page as martian driver kit, and must be assembled with gcc 4. If you have to do this but have no 32 bit Linux system, I can send one via e-mail feature. Don't be shy to ask for more info.
Good luck,
http://linmodems.org/
Installing WinModem Driver in Mandriva 2007
