It started with printers. The industry learned that they could reduce the cost of a printer by handling the intelligence in a software driver on the host computer, rather than embedding a sufficiently powerful computer in the printer.
The same thing is now happening with modems. Rather than building a new modem chipset every time a new protocol comes out, and buying such a chip for every modem produced, a "modem" can become a generic interface to the phone line, and the modulation/demodulation of an audio signal can be done in software which resides in the modem driver
It's a great idea, with one drawback: modem drivers are operating system specific, whereas modems previously were not. This means you have to produce drivers for every operating system that the modem will be used with, or choose the monopoly operating system and ignore the rest. I'm sure you can guess which route the vendors took.
In short, WinModems don't work with FreeBSD. In the Linux world, some effort is being put forth to mitigate the problem, but much of that work does not port well to other Unixes. For instances, a couple of vendors have been convinved to release binary kernel modules for Linux.
The place to read up on this subject is at linmodems.org, however there doesn't seem to be much momentum there. There hasn't been much progress since the last time I looked their eight months ago, and now a number of the links are stale.
I appear to have a "SoftK56 Data, Fax PCI Modem" from Conexant Systems (formerly Rockwell). There doesn't seem to be any solution for me, even if I was running Linux instead of FreeBSD.
The moral of the story is, pick your hardware wisely. Unfortunately, for laptops at least, WinModems seem to be the prevailent standard.