Voice over Internet Protocol or VoIP is also known as IP telephony. It is a group of technologies combined that delivers voice communication and multimedia sessions over the Internet Protocol networks. The terms broadband phone service, broadband telephony and internet telephony refer to the provisioning of communication services (SMS, voice, fax, voicemail) over the internet, instead of using Public Switched Telephone Networks also called Plain Old Telephone Services. The principles and steps involved in making VoIP phone calls are the same as traditional digital phones. It involves signalling, setup of channel, analogue voice signals digitization and encoding. Rather than transmitting signals over a circuit-switched network, Voice over IP makes digital data packets and transmits those IP packets over a packet-switched network. IP telephony transmits media streams over particular protocols for media delivery that encodes audio and video using audio and video codecs. Different codecs optimize the media stream depending on application requirements and network bandwidth. A few implementations depend on compressed speech and narrowband, while other support high fidelity stereo codecs. Other than VoIP phones, this technology is also available on personal computers and other internet-enabled devices. Voice and video calls, and SMS can be made through Wi-Fi or using mobile data network. Voice over IP provides a framework to all modern communication technologies through a single unified communication system.