Voice over IP (VoIP)

Voice over IP

Voice over Internet Protocol (Voice overIP, VoIP and IP telephony) is a methodology and group of technologies for thedelivery of voice communications and multimedia sessions over Internet Protocol(IP) networks, such as the Internet. The terms Internet telephony, broadbandtelephony, and broadband phone service specifically refer to the provisioningof communications services (voice, fax, SMS, voice-messaging) over the publicInternet, rather than via the public switched telephone network (PSTN).

The steps ad principles involved inoriginating VoIP telephone calls are similar to traditional digital telephonyand involve signaling, channel setup, digitization of the analog voice signals,and encoding. Instead of being transmitted over a circuit-switch network,however, the digital information is packetized, and transmission occurs as IPpackets over a packet-switched network.

Early providers of voice-over-IP servicesoffered business models and technical solutions that mirrored the architectureof the legacy telephone network. Second-generation providers, such as Skype,have built closed networks for private user bases, offering the benefit of freecalls and convenience while poetically charging for access to othercommunication networks, such as the PSTN. This has limited the freedom of usersto mix-and-match third-party hardware and software. Third-generation providers,such as Google Talk, have adopted the concept of federated VoIP – which is adeparture from the architecture of the legacy networks. These solutionstypically allow dynamic interconnection between users on any two domains on theInternet when a user wishes to place a call.