Currently, there are several VoIP services on the market -- the two most well-known ones are Skype and Vonage. Although they both use VoIP technology, they're quite actually quite different from each another.
Over the last 20 years or so, fiber optic lines have taken over and transformed the long distance telephone industry. Optical fibers are also a huge part of making the Internet available around the world.
One of the relative miracles of modern times is the reliability of the phone system. The power goes out fairly often for most people, but your telephone is always working (as long as you pay the bill). Why is that?
When you make a long-distance call, there is an amazing amount of technology working to make your call happen. To understand the computerized systems used today, it's helpful to go back in time and look at how long-distance calls were first routed.