Hi,
I have just installed Fedora Core yesterday and encountered the following problem:
The wvdial is not able to connect to the Internet as a normal user. However, root can connect.
The following messages appeared in the terminal:

--> WvDial: Internet dialer version 1.53
--> Cannot open /dev/ttyS1: Device or resource busy
--> Cannot open /dev/ttyS1: Device or resource busy
--> Cannot open /dev/ttyS1: Device or resource busy

In the same machine I have JDS and to get wvdial to connect as a normal user I performed the following two commands as a root:
chmod o+r /etc/wvdial.conf
chmod +s /usr/sbin/pppd

I tried to do the same thing under Fedora but it did not work.