Hey!
I have the same problem, but I'm dialing-up with the ISDN terminall connected to the USB port on Fedora 1. Everything goes fine untill I try to acces the internet!
... even the ping, traceroute doesn't work ...
Looks like there is a buggy kernel, because I've once seen a message like:
serialusb.c - To much data ...
Any solution for me and the upper post
?