If you want to save money on your telephone service using the internet, you will need to sign up with a VOIP (Voice Over Internet Protocol) service provider. They will sell you the necessary equipment and assign you a number, which is used like a regular phone number.
VOIP providers are useful and very cheap. Most providers offer VOIP connections free of charge. They make their money by charging for calls to the regular telephone network. Most providers allow you to call any phone number in the world for a moderately low fee. For modest monthly fees (about $8-$20), they offer unlimited calls to certain geographic areas. They also provide voicemail, call forwarding and conference calls, at no extra charge.
Vonage, BroadVoice, Diamond, iConnectHere, Lingo, mywebphone, Packet8, and VoicePulse are some of the major VOIP providers. Most of these companies are based in the United States; some also have offices in other countries.
VOIP equipment includes a broadband modem and an ATA (Analog Telephone Adapter) or IP phone. Both the ATA and IP phone connect directly to the modem, but the ATA allows you to use older analog phones. No matter which equipment you use, it has a unique number that identifies your current IP (Internet Protocol) address. If you're constantly on the move, your VOIP provider tracks your current IP address, which allows people to contact you no matter where you are.
Even if you're using your Internet phone from a single location, a VOIP provider is usually still necessary. The majority of residential Internet connections have 'dynamic' IP addresses, so every time you reconnect to the Internet, you have a different IP address.
The VOIP provider is also useful, because people can contact you by entering your user name, rather than your IP address.
When choosing a VOIP provider, keep in mind the protocol they use. SIP seems to be the emerging standard. It offers fairly easy connection routes between different VOIP providers. H.323 and IAX protocols are sometimes offered in addition to SIP. Skype, popular for PC-to-PC VOIP systems, uses a proprietary protocol, so it is not easy to connect to the Skype network from another VOIP provider.
It is a bit of work to research and set everything up, but the sooner you start, the quicker you will be able to look back and say, "Why did I wait so long?"

About the Author
Ron King is a full-time researcher, writer, and web developer. Visit http://www.voip-solutions-now.com to learn more about this subject.
Copyright 2005 Ron King. This article may be reprinted if the resource box is left intact.