Patching the kernel has worked in the past but no patch seems to be currently available. Check out the website for it. There are many Linux users that say that it's a lot simpler just to get an external modem and plug it in. Since you usually plug the modem into a serial port which has its own IRQ number and IO address, the modem needs no PnP features to set these up. Such an operating system would then know that you have a modem on a certain port and would also know the model number.
Modems use straight through cable, with no pins crossed over.
Most computer stores should have these. Make sure you get the correct gender. If you are using the DB9 or DB25 serial port at your computer, it will always be male which means that the connector on the cable should be female. Hook up your modem to one of your serial ports. If you are willing to accept the default IRQ and IO address of the port you connect it to, then you are ready to start your communication program and configure the modem itself.