In /etc/security/concole.apps/isdn-config there is a line
FALLBACK=true to enable a normal user to run the program even ehen
authentication as root fails. But the program itself fails to run
when not run as root. When a user starts isdn-config and he clicks
on "run unprivileged" isdn-config complains about not being root
So this parameter should be FALLBACK=false to hide that "run unprivileged"
It's fixed in isdn-config-0.17-9.