SIP Architecture

As the Internet became more popular in the 1990s, network programs that allowed communication with other Internet users also became more common. Over the years, a need was seen for a standard protocol that could allow participants in a chat, videoconference, interactive gaming, or other media to initiate user sessions with one another. In other words, a standard set of rules and services was needed that defined how computers would connect to one another so that they could share media and communicate. The Session Initiation Protocol (SIP) was developed to set up, maintain, and tear down these sessions between computers.

By working in conjunction with a variety of other protocols and specialized servers, SIP provides a number of important functions that are necessary in allowing communications between participants. SIP provides methods of sharing the location and availability of users and explains the capabilities of the software or device being used. SIP then makes it possible to set up and manage the session between the parties. Without these tasks being performed, communication over a large network like the Internet would be impossible. It would be like a message in a bottle being thrown in the ocean; you would have no way of knowing how to reach someone directly or whether the person even could receive the message.

Beyond communicating with voice and video, SIP has also been extended to support instant messaging and is becoming a popular choice that’s incorporated in many of the instant messaging applications being produced. This extension, called SIMPLE, provides the means of setting up a session in much the same way as SIP. SIMPLE also provides information on the status of users, showing whether they are online, busy, or in some other state of presence. Because SIP is being used in these various methods of communications, it has become a widely used and important component of today’s communications.