Voice over Internet Protocol (VoIP) is a group of technologies for the delivery of voice communications over Internet Protocol (IP) networks, such as the Internet. The term Internet telephony (=VoIP calls) specifically refers to the provisioning of communications services over the public Internet, rather than via the public switched telephone network (PSTN), i.e. traditional telephony. The steps and principles involved in originating VoIP telephone calls are similar to traditional digital telephony. Instead of being transmitted over a circuit-switched network, however, the digital information is packetized and transmission occurs as Internet Protocol (IP) packets over a packet-switched network.