Powerbook G4 internal modem not found?

I'm doing my first round of testing of Leopard on what I had handy -- a 15" Al Powerbook G4. It has an internal modem, but Leopard doesn't seem to know it's there. System Profiler doesn't see it, and I don't get an option to add it in the Network Settings Preference Pane and Z-Term doesn't see it either. I see that there are internal drivers, so I'm assuming that it's because the system doesn't think it's there.

Now I haven't used it for a while, but it really was working the last time I needed it a few years ago, and there's no reason to think it has failed.

Plugging in an external USB modem does show up in the Network Settings pane

I searched the threads and noticed a few side comments that other people lost their G4 modem interface, but no followup on any of them. Anyone else having this issue, or even better have you figured out how to make it work?

-debbie