I bought this vphone at Best Buy for $29. You can use it against an already existing Vonage line. You can easily switch the hardware for your line from your home adapter to the vphone on the vonage account website. Worked great for us on our last trip to Athens. All phone calls were free with outstanding quality. The only requirement is an internet connection and since this is a usb device you can use it on other devices, ie. the hotels business center computers......