ISDN and redhat-control-network

[Luca]

Hi all,
I have to report some problems with my FC1 install.
I have an HFC-PCI nameless ISDN card, that got found and configured on 
install.
When accessing redhat-control-network, the card can be found, and the 
connection comes up without any glitches.
Problem is, the ippp0 interface does not get detected as being up, so I 
can connect, but not disconnect!
It's not a major problem, but since I don't have a flat rate phone 
contract, I usually only connect when I need it.
This e-mail is mainly to report the bug, but I'd also appreciate if 
somebody could tell me how to bring my ISDN connection down (and up, but 
that's less important) by command line, to avoid going broke on phone bills.
Thanks all,
Luca