Modem IRQ

I recently had RoadRunner installed. In the process of this I lost my dial-up modem. The IRQ went from 3 to 11 and everything that I have tried has failed to change it to make it compatable with a COMM port for use. I do have cable access but I still use my dial-up for faxes. Is there a fix short of pulling the plug on the BIOS and having it reset itself? No help from the manufacturer of the computer, Microsoft, and unable to contact the maker of the MB and Bios.