If you arrived at this page, probably you want a Modem driver for Linux. (If you want information on Ethernet drivers, see here).
The modem in the 3Com Mini PCI adapters is a winmodem, and
there are no drivers that work on Linux. Long ago, 3Com was
looking for feedback on whether it should write a Linux driver
for the modem, see here.
If you have interest in using the modem on Linux, write them one
short and polite message (that's enough, believe me).
As soon as a driver for the modem becomes available, I will post information on this page, so please check it periodically (please don't e-mail me asking when drivers will be available, I don't know! And in case you are wondering, yes, this page is kept up-to-date). And needless to say, if you find any information about a driver for this modem please contact me.
(Before giving up, just in case, assure yourself that the modem in your computer is the 3Com Mini PCI modem, which has 3Com as the manufacturer and a PCI Device ID of 1007. Some IBM ThinkPads seem to have the 3Com Mini PCI Ethernet adapter and the Lucent modem, which works on linux. The instructions on how to make this modem work are here; thanks to Stefán for the link!).