Is your modem a pci slot one or external (or ISA)? You may find that you have a winmodem, specifically designed to work in windows and it will have drivers for it. If it is, what type does it say it is in windows (i.e. HCF? HSP?). If you find out then goto http://www.linmodems.org
and have look at the website for help.
This is only if you have a 'winmodem' or 'softmodem'!