Ltmodem on Gateway Solo 2150

Gateway Solo 2150.
Redhat Linux 6.1
Kernel 2.2.19-6
Modem: Actiontec 56k
Chipset: Lucent (0x11c1, 0x0448)
Ltmodem: 5.99b
Problems: required setting Operating System in BIOS from Windows to Other (meaning: the BIOS, not the O.S., initializes PnP devices).
Parameters detected by kernel: IRQ 3, Port 0x1400, Port 0x10e0
Trying to leave OS as Windows and forcing these parameters does not work, reason unknown.