www.dns2go.com - they provide a nice little program that dynamically monitors your IP and creates a static name - yourname.dns2go.com
So you'd be able to map at least one of your addresses to a static name and depending on how you router works that may or may not help you. I've been pushing my gnutella client (limewire) to a name rather than an IP with the same results as me changing the IP # everytime.
But I'm not really knowledgeable about ISDN so I can't really speak about how you'd go about mapping it all.