Try a PCMCIA upgrade
Xircom PCMCIA Ethernet Adapter Issues
CBEM56M at irq10/port1480 "modem is busy"... HELP! (Albert S. Johnston)
Date: 2000, Feb 09
From: David Hinds <email@example.com>
I'd suggest upgrading to the 3.1.10 PCMCIA drivers. I think the modem
problem is a symptom of a bug in the kernel serial driver; there is a
workaround in the current PCMCIA package.
SUCCESS!!! by Albert S. Johnston, 2000, Feb 10
to: "Try a PCMCIA upgrade"