That's a so-called software modem; a piece of hardware that does most everything other than driving actual electrical lines on the wire in software rather than hardware including (potentially) presenting a serial port interface. In this, "software" equals "the Windows driver". There's been valiant attempts at reverse engineering latter but this subject is now completely and fully historic.
I'd be surprised if you could get it going with a modern kernel, in which "modern" is anything more recent than a 2.6 series kernel, i.e., 10+ years ago. If you'd insist on trying you'd start at https://www.linuxant.com/drivers/hsf/install.php
--- but I would also note that Conexant not supporting Linux in any shape or form was together with their "hardware" being anything but
hardware historically enough reason for most Linux users to not bother with them in the first place,
If you are doing more than playing and were using a system providing an actual external serial port (which I guess you are not) I'd really
advise grabbing an external serial modem, i.e., a real one. Doubt you'll still be able to do anything with that bit of non-hardware that you currently have. Maybe USB hardware modems exist? No idea...