ZDNet AnchorDesk: What's wrong with Internet phones:
"The best thing about the traditional phone system is what people take for granted: Any phone on the planet can connect to any other. Some Internet telephone systems, such as Vonage, can also connect to any other phone. But except in extremely rare cases, two people on different VoIP systems can't connect to each other directly over the Internet--they have to use the public phone system as a go-between.… "

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