I can test with you. Check your private message. I have had no problem with the Skype billing time. A Skype call anywhere in the world to anywhere in North America it is 1.7 euro cents and I buy buckets of $20 euros. I use this on my PDA as a conveniece phone when on trips or if I call during the day where day minutes is limited to 350 mins. on my cell phone. My friend has been using Skype for the past year calling Portugal and Poland and has had no issues. This is more of convenience phone scenerio. The Vonage system would be more of a cell/landline replacement/alternative. There are actually Voip/IP phones that look like cells but are 100% hardware voip. They connect to SIP networks.
http://www.voip-info.org/wiki-VOIP+Phones#id515213
http://www.slashphone.com/70/642.html
Not yet really popular but I see it more widespread in the next couple of years as an alternative to cell when cities become city wide wifi.
http://www.google.ca/search?hl=en&q=city+wide+wifi&btnG=Google+Search&meta=
