Is It Possible To Connect AT&T CallVantage Behind A Router?

Archived from groups: comp.dcom.voice-over-ip (More info?)

I'm thinking of subscribing to CallVantage. From what I read, one
thing that concerns me is their D-Link telephone adapter looks like it
has to be installed between my cable modem and router.

My concern's are:

I have a web server on my network using a dynamic DNS service
(DNS2GO). Its local IP is the one entered into my router that "pokes
through it (DMZ)." It's used for development, and not really used
much to serve pages over the internet, but from my understanding, when
I want someone to browse something on my webserver, I'll need to
remove the telephone access device each time and plug the router back
into the cable modem. Otherwise the router will only know about the
local IP being fed to it by telephone adapter.

I sometimes also use a service called RealVNC for remote accessing my
network. The same problem will happen here too. NetMeeting the same,
although I don't really use that service.

So I need suggestions on what to do, configuring my router (a Linksys)
and telephone adapter.