router thru a router

I have a linksys 4port cable/dsl router hooked up to my cable modem and I
have just purchased vonnage... they sent me another 4 port unit with the
phone line incorporated to that router... my question...

in the documentation it states that I can plug the new router into the old
router.. however I can not use any of the new 4 ports... Is this just
because you would have to go into the web browser utility and change some
settings?

In my old set up I am using ftp and gaming so I do set static addys for the
computers and disable dhcp

couldn't I do the same basically for the new router? or have I hit the crack
pipe a little early this morning?

thanx

snc