With the appearance of the Internet as an important communications medium for widespread everyday use, which can be dated to the mid 90s, a need to establish a signalization protocol for multimedia communications was recognized. There were two major proposals: SIP by the Internet community, and H.323 by ITU-T.
The Internet Assigned Number Authority (IANA) Uniform Resource Identifier (URI) Parameter Registry for the Session Initiation Protocol (SIP)
