Not sure if there is a driver that works for Fedora. Does the modem have a serial port on it also?
Most Windows modems don't work well in linux because they are software modems, i.e. someone wrote some code for windows as to how windows can talk to this modem. Most of these sets of code don't work on linux because the drivers are closed and no one has been able to reverse engineer the driver.
Generally, in linux you want an external modem that uses a serial port because these are hardware modems and contain their own chip to do the processing. So the operating system only has to know how to use standard serial port communication (which is a published standard) to make the modem work.
So I guess, in closing, unless your modem has a serial port (not just the USB port in their documentation), I'd google my brains out to see if you can find a driver (although I'm not optimistic) or buy an external serial hardware modem...