quickstart, I think we are twins, but I use an US Robotics (USR 9105).
But seriously, I think that the USB modems should be supported out of the box (at least Thomson provides firmwares/microcodes/drivers free of charge, but closed source). Moreover, believe or not but British and Polish phone standards are exactly the same. Our "beloved" national monopolist (aka known as national operator, something like BT in the UK) decided to not reinvent the wheel but copy the standards of one Western European country. By coincidence it was Britain.
Why do I think it is so important? Well, quite a lot of my friends want to install (or at least try) Linux. The problem is that they own the modems supplied by their operators (almost all of them!). Of course they fail with the installation and ask me for help. I explain them how it works and they tell me something like that: "Wait a minute, nobody told me that I will have to spend quite a lot of money for a router. I thought that Linux is free as a beer and does not have any hidden costs. It makes no sense if I have to spend money for a router which costs almost the same as a copy of Windows".
And I have to admit that they are damn right. The Net must be installed out of the box, it is far more important than any other driver. Why? One can install the rest of drivers from repositories and/or if some good souls from help forums will help him. But he must be connected the Net anyway. What I see today is a weird situation, there are more and more drivers for different hardware included, but not the modems. I am a Linux enthusiast so I bought a router, but I do not want to force anyone to spend money, so answer them "Yes, I think you are right. Do not spend your money and forget Linux as long as Linux forgets you".