What form of communication does SIP primarily support?

SIP, or Session Initiation Protocol, is primarily designed for initiating, maintaining, and terminating real-time communication sessions over the internet. It is a signaling protocol that facilitates voice and video calls using the Internet Protocol (IP), primarily enabling Voice over Internet Protocol (VoIP) services. VoIP allows users to make voice calls using a broadband Internet connection instead of a traditional phone line, which is a central function of SIP.

SIP manages the setup of calls, the modification of ongoing sessions, and the teardown of calls when they are completed, making it essential for voice communication in various applications, such as IP telephony, unified communications, and other VoIP services. While SIP can support other types of media, such as video conferencing and data transfer, its primary and most recognized application is in VoIP communication, where it handles the signaling necessary to establish and control those sessions efficiently. Thus, the focus of SIP's capabilities firmly aligns with VoIP as the primary form of communication it supports.