When you are using "isdnconfig" and you have selected your card, you are going to select an "ISP". Then you get a list over known "ISP`s" in your country. But if your ISP isn`t there you have to create a new. But when you try to do that you just get the upper line (the blue line where it stands what program and so on that you are in, un top of the windows) of the windows. And when you dubble- click on it, you can see a black shadow from it, but you can not do anything there. So when that dos`nt work, you can`t select your own ISP, and than you can`t connect to the internett with your isdn- card. I am using Eicon Diva 2.xx ISA (PnP).
It was a bug in Qt. you should update the final qt-2.1.0. It fix your problem.