I incorrectly identified my Xircom card. It is, in fact, an RBEM56-100. Also, when I start my machine, it beeps twice at the same pitch in an indication that everything has started correctly. The modem settings (by doing a setserial -a) appear to be correct. It just isn't working properly. I have tried to set it to polling mode and then back to its assigned interrupt, then I have tried changing the port to match the one shown by cardctl config. Neither seems to do anything. Any suggestions are appreciated!