According to
this page, your modem's chipset is Conexant and is indeed a "Winmodem." Conexant has shown little if any interest over the years in supporting their products under Linux. There is a company called
Linuxant however that makes Linux drivers for these devices, but at a price. They aren't greedy, they just have to eat too.
If it is an option for you, perhaps also consider buying a good external usb/serial modem, most all of which work with Linux. Besides, you'll get better connectivity and performance from an external modem in Linux AND Windows. I have used (and recommend) the
Actiontec V92 external modem. They are very affordable and give years of dependable service. You can also pick one up off
eBay for less than ten dollars but you have to factor in the high cost of shipping.