A Look at Session Initiation Protocol

From: The VoIP Essentials Series

By: Ken Camp

This article begins an exploration of common VoIP protocols. This first installment of an ongoing exploration of the technical workings of VoIP protocols will explore Session Initiation Protocol (SIP). As this is the first paper in the series, it will begin with an overview of how the open standards widely used in the Internet are developed.

Standards used in the worldwide Public Switched Telephone Network (PSTN) are products of the International Telecommunications Union-Telephony (ITU-T) sector, formerly known as the CCITT. This group operates under the auspices of the United Nations (UN), which is important to note because this body acts in many ways as an administrative unit focused more on international interoperability than other areas. Although this group has responsibility for telephony standards, they have not historically been known for being quick or nimble at responding to technology needs. ISDN standards took 10 years to get through this group. There are many different international political agendas that come into play when dealing with the UN, and change takes time.

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