I know that it's understood that Linux doesn't operate with the winmodem.
However, I've heard that with some modems it's now possible.

The modem I'm trying to use is Diamond SupraMax 56i PCI.  According to the
following link, I can use an LT WinModem (from Lucent).

Supports: ISA/PCI modems, with Lucent chipsets (Mars family)

Can any other modem, particularly the one I'm using actually work?

http://www.linuxdoc.org/HOWTO/Winmodems-and-Linux-HOWTO-3.html

Mark