I cannot connect to my ISP with Linux.
First I though it was a problem with my ppp software, then I though it might be the dialer, now I'm sure it's the configuration of the port itself.
I could say a lot about the symptoms of my problem, but the gist is this: my serial port (/dev/ttys0) configuration is set for the right irq (4), Linux never complains about any conflict, but every program I have used from minicom to gppp or kppp always says that the modem is busy.
Whether the modem is on or off, every dialer tells me the modem is in use. According to /proc/interrupts, the irq is used only by the serial port, but the lights on the modem never blink with Linux. Minicom doesn't report any errors when it's initialising the modem, but if I try to dial, it tells me that the modem is already in use and that I have to hang up. Again, whether the modem is actually on or off makes no difference. The modem works perfectly with windows, so the modem is not the problem. It's an external USRobotics 56K Faxmodem. Not a Winmodem.
Configuring the BIOS to "non Pnp OS" doesn't change anything. According to a command called "fuser" (I'm still new on Linux and I'm not sure what is exactly is) there are no programs using /dev/ttyS0 other than the dialers, whenever I use them. There is only one serial port on the computer, so there are no conflicts there.
Since I never found anyone who could provide a solution, this problem is probably more of a challenge than it seems. And if it is not, that's all for the better.
Thanks to anyone who has a solution.