Trying to start kisdndock as a non-root user gives the following message: $ kisdndock The KDE libraries are not designed to run with suid privileges. ERROR: KUniqueApplication: DCOP communication error! As the main purpose of kisdndock is to allow regular users to connect/disconnect ISDN, this bug makes it useless.
It's fixed in kisdndock-0.9.0-3. It will go into next rawhide release.