Absolutely, you need to get a BRI interface for your router and order your ISDN line...
When you get that let us know and we can help you configure it, the only advice I'm gonna give you for now is...
config t
no ip dns look-up
^z
That is the MOST annoying feature with ISDN back-up on a router. If you are on the command line and type;
soh log (instead of sho log)
it brings up the ISDN because soh isn't a command so it must be a DNS name and it has to search every interface for it.
AidanEnos