Internet Voice Servers
Using the Internet, you can almost create your own phone company! If you need more control than you can get with Vonage or Skype, you might consider hosting your own Internet Voice Server. Popular servers include "TeamSpeak" and "Ventrillo".
If you want to make your Internet Voice Server available on the worldwide Internet, you should be very careful to restrict access. You can learn more about the basics of Internet Servers from other movies at AskMisterWizard.com, including these: