This chapter describes the motivation that led to the development of SIP.
Initially, Private Branch Exchange and Central Office switch-based telephony system were the main instruments for transmitting voice, however, the Internet has change that. As IP bandwidth increased, methods were sought that would enable customers to use some of the bandwidth for voice as well as data. The ability to combine voice and data over the same physical medium offered the promised to reduced the operating and plant cost. Several solutions for combining voice and data were put forward, but the solution presented by IETF (Internet Engineering Task Force) was finally accepted as the standard. The development of SIP evolved over several years.
Initial Internet drafts were presented in 1996 with improvements occurring over several years. In 1999, SIP published RFC 2543 as a standard. Later it was modified and a more up-to-date version was published: RFC 3261.
Parent topic: SIP Overview