Right.
Installing an incompatible module has possibly screwed the OS. . .Lets hope not.
Install Minicom, you can find it on killefiz.de/zaurus
run "cardctl resume"
"dmesg"
If it mentions a card being allocated a serial port, You're off to a good start, and your OS has probably survived. If not, run "cardctl status" If it's giving any wierd errors, about bad VCC, then your card is not being assigned with the 16650 driver that it should be. . I can;t help you there, I only use 2.4.18. A c1000+ user should be able to help you.
If everything looks good, then I have no clue why it won't work.
If you've got a serial port, run "minicom -s" (ROOT) set up your serial port as "/dev/modem" with baud 9600
make a phone call attempt with "ATDT<YourHomeNumberNotTheZaurusNumber>" Your home phone should ring.
If that's fine, you should be able to just use the old init string from the 5500 setup, get the setting the same manually, and connect!