Hi,
No, not at all was I suggesting that you subscribe to vonage. I was simply stating that I use my vonage in a similiar fashion to what you described wanting to do with the IPTV box.
The DIR-655 is not really meant to be an access point, altho I believe that some folks may well use it in that fashion, altho I can't tell you how they may have gotten that accomplished.
I have used successfully a powerline networking "extension" of my home network, it is akin to wireless networking but uses your home's power lines to pass the signal over to another part of your home. I would think with a TV signal over IP you would want the newest Powerline hardware which runs at some "roughly" 240 Mbps (Mega-bits-per-second) by the math (real world will likelt be less than the mathematical speed).... My powerline hardware is older and the speed is only like 14 Mbps which is fine for my XBox360 that uses it.
Wireless .11N has a "math" speed of 300 Mbps, but who knows what your real world might deliver due to the requirements for the 300 Mbps to be realized by .11N hardware.