What is Internet Telephony (VoIP Telephony)?
A category of hardware and software that enables people to use the Internet as the transmission medium for telephone calls. For users who have free, or fixed-price Internet access, Internet telephony software provides free telephone calls anywhere in the world.
Internet telephony can be any means of transmitting the human voice (real time or close to real time) over the internet. There are several components. On the client side, a multimedia-equipped PC with special client software will digitize your voice. This can be done with a voice modem or other voice encoding method; second, a direct or dial-up connection to the internet allows your voice to be transmitted in packet form to its destination. Third, a connection with the far side is achieved by IP address search, common servers or beacons to identify the called party (and to "ring" that person's phone). Fourth, a similar arrangement on the far end completes the call and allows both parties to speak.
There are also PSTN/Internet gateways that allow regular telephone callers to make Phone-to-Internet-to-Phone connections. There are PC-to-Phone connections and Phone-to-PC connections. To date, however, Internet telephony does not offer the same quality of telephone service as direct telephone connections.