what is sip

The Session Initiation Protocol (SIP) is a signaling protocol used for initiating, maintaining, and terminating communication sessions that include voice, video, and messaging applications. It is used in Internet telephony, private IP telephone systems, and mobile phone calling over LTE (VoLTE) . SIP is a text-based protocol, incorporating many elements of the Hypertext Transfer Protocol (HTTP) and the Simple Mail Transfer Protocol (SMTP) . It supports voice calls, video conferencing, instant messaging, and media distribution. SIP is used to transfer calls, terminate calls, and change call parameters in mid-session, such as adding a 3-way conference. SIP trunking, on the other hand, is the digital way of making and receiving phone calls and other communications over an internet connection, utilizing SIP. In summary, SIP is a crucial protocol for enabling various forms of communication over the internet, including voice and video calls, instant messaging, and media distribution.