SIP stands for Session Initiation Protocol, which is a signaling protocol used for initiating, maintaining, and terminating communication sessions that include voice, video, and messaging applications. SIP is used in Internet telephony, in private IP telephone systems, as well as 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) . SIP is used to transfer calls, terminate calls, and change call parameters in mid-session (such as adding a 3-way conference) . SIP is a core component of VoIP, the technology that allows you to make and receive calls over the internet. SIP addresses are similar to an email address that allows you to be identified by your real-time IP. SIP addresses are used to find a users network location so communication can happen anywhere and anytime.