The listing, PCI Modem has ended.
PCI Modem - HP P/N 5188-2907
This was bundled in the desktop that I got for my mother-in-law Christmas before last. I pulled it from the machine when upgrading a few components as it was never used.
Since the machine was an HP originally running Vista, finding drivers other than Vista may be a hassle. (I gave it a cursory look and saw some links, but did not follow-through to check them out.)
The silkscreen has an FCC portion that reads "Trade Name: Conexant Model name: RO01-D850 US CXSM502BRDO01D850" (I'll warn you the print is small and my eyesight is not that great.)
The RD01-D850 is repeated on the board, which should help in finding drivers quickly.
Free shipping in the US only.