I have a similar problem with my Xircom RBEM56G-100 on RedHat 6.1 with kernel 2.2.12 and a Dell Latitude CPt400G. Card Services start ok and the network half ot the card is fine. The modem side is assigned to tty00 according to dmesg. When I look at the system log it shows the card started on ttyS0 at irq3. These settings should work but when I try to access the modem I get a modem busy message. I've looked for some sort of lock but can't find one. This same hardware worked very well with RedHat 5.2/Kernel 2.2.7/pcmcia-cs-3.0.14. Have I missed something in the configuration?
Thanks, Rick Knight (email@example.com)