http://www.sunrocketforums.com has a lot directions for this.

http://www.sunrocketforum.com/viewtopic.php?t=1310&highlight=inside+wiring

Very easy

on the outside of your house should be a network interface box–should be black or grey and have a bell picture on it or your phone company’s logo……… open the box (yes, this is legal, this is how you would isolate your phones during troubleshooting—the part you can access is exposed and the part they don’t want you to access is boxed in, inside this box) and you should see a familiar looking phone plug. unplug this and you will isolate your inside phone wires from the telephone company’s network. Make sure you put a note on the cable saying “DO NOT PLUG–VOIP in use.”
If you do not have one of these boxes on the outside of the house, find where the phone company’s wire comes into the house and disconnect this source. The old school way of doing this was running a wire to a phone block which may be in the basement or in the attic space for example.

Get a phone splitter from Radio Shack. This will be a small plug that you plug into your wall jack to make 2 jacks out of one. Plug your phone line from the phone port on the phone router into one of the split plugs that you just plugged in.

You are now VOIP using your inside wiring. What you just did was make your plugs live from the inside as opposed to the phone company input from the Network interface.

Do not skip the first step of isolating your inside wiring from the telephone company wires………you WILL damage your phone router!