I have been using Vonage with a DS7000 for over a year now without having done anything unusual to make it work. I have the standard Vonage package (no data line) and it dials out just fine. I am using Comcast for my internet provider in case that makes any difference.
My setup is Comcast cable internet connection, Motorola SB5120 Cable MODEM, Linksys WRT54G wireless router, Linksys Vonage phone adapter model PAP2. The router is configured to provide high priority to the port that the Vonage phone adapter is physically connected to.
Other than that, I have not installed any filters or had to make any other changes. The DS7000 is configured to dial out 4 numbers with the format 1-xxx-xxx-xxxx.
Hope this helps
Bob