You'll never see PCI ADSL modem support for 90 percent of the hardware out there. It's all soft-modem HSP/DSP type hardware that requires the driver to do the brunt of the work. Each time the driver loads it has to 'program' the firmware into the card soft loading instructions. By themselves the ADSL PCI cards are completely dumn. Some of the external USB modems are a bit smarter and just require the right generic usb driver and instructions sent via the usb data connection. That's probably why there's one working for m0n0wall.
But if you're expecting winmodems to work in a freebsd firewall, you're probably wishing for something that will never come. Well I say never, but Connexant could start writing freebsd drivers for their cheap, neutered, and otherwise dumn hardware some day. You never know...
The only reason Lucent DSP modem hardware worked in linux is because lucent released some framework for their soft modems for use in linux.
That's my 10 cents and change. It's much the same as the wireless hardware out there. None of it will run very well without very specific firmware based drivers.