Voice over IP (VoIP) is a telecommunication service that uses packet switched network infrastructure such as the Internet to facilitate interactive voice communication using telephone or computer. It allows people to make phone calls through data network. It is an IP based voice transmission technology. VoIP transmits packets via packet-switched network in which voice packets may take the most efficient path. On the other hand, the traditional Public Switched Telephone Network (PSTN) is a circuit-switched based network which requires a dedicated line for telecommunications activity.