Raffi Krikorian’s review of Vonage’s Voice-over-IP phone-service is a great, info-civilian-oriented overview of the best way to secede from your phone company.
The Edison, New Jersey based company gives you one Cisco ATA186 and a phone number in an area code of your choosing (I had a little piece of northern New Jersey in my living room). You have a choice of two different levels of service to go along with this box: for $25.99/month you get unlimited local/regional calling (where local/regional is defined by the area code you choose for your phone number) and 500 minutes of free US long distance, and for $39.99/month you get unlimited long distance. And you also get international rates that rivals most common calling cards. The only problem is that the service only delivers one ATA186, and that specific model is required to use the service — no other SIP compatible devices are supported yet. If you want to use more than one phone with the box, you will either have to rig up a network of telephone splitters and wires; or you can do what some have done and hack your house to plug the Cisco box into your house’s in wall telephone network.