How the phone companies are trying to push out VoIP
The business world is littered with monopolies trying to block new competitors through any means possible, and one effective strategy is getting the government to intervene. This is why satellite TV couldn't carry local channels for years. It's why Southwest Airlines can't fly out of certain airports. It's why MCI had troubles using microwave repeaters to compete with AT&T. And it's also why XM radio can't do local weather or sports. In each instance, the incumbent had to get a law passed or a government body to impose regulations devised to slow or stop new competitors.
For VOIP, certain telephone companies went to the FCC and pushed them to demand that certain net calling companies provide e911 to their customers. They knew that this would add costs to their business - and perhaps even be unfeasible - since precisely determining the location for a computer on the Internet can be impossible.