Regarding VonageFollow

you want the vonage thingy behind the router so that nefarious beings cannot hijack it and use your vonage account to call pakistan or something. It will work fine ahead of the router other than that.

As far as disconnecting the phone from outside line and running into vonage box, yes, you "can" do it, and yes, assuming we aren't talking a 17 century house of some sort, you should be able to make it work. The real question is do you know how to do so. I always found it easier to just plug a wireless telephone base into the vonage type device and leave the house wiring intact in case I ever wanted to get DSL instead of cable.

that box is generally going to have at least one wiring block inside of it, with most likely 4 different colored wires coming to the block from a cable delivered by the phone company, and another 4 wires running from that block into your house. Those are the 4 wires that run to your phone jacks. Chances are there may be one set running to that same block for different rooms. You basically need to go out from the vonage device to those wires, and disconnect the wires comeing in from outside the house entirely. Here's a tutorial. http://www.engadget.com/2006/06/20/how-to-wiring-voip-to-your-phone-jacks/

Good luck!