Voice over Internet Protocol, or VoIP, allows one to make telephone calls using a computer network, over a data network like the Internet rather than a public switched telephone network. VoIP converts the analog voice signal from your telephone into a digital signal that travels over the network then converts it back to at the other end so you can speak to anyone with a regular analog phone.
Currently, the most promising areas for VoIP are corporate intranets and commercial extranets. Their IP-based infrastructures enable operators to control who can and who cannot use the network. Corporations can reduce expenses associated with high-volume voice, fax, and video conferencing traffic.
The economics of placing all traffic- data, voice, and video- over an IP-based network will pull companies in this direction, simply because IP will act as a unifying agent, regardless of the underlying architecture (i.e. leased lines, frame relay, or PRI) of an organization’s network.