The full form of ITU in standards is the International Telecommunication Union. It is a specialized agency of the United Nations that focuses on developing international standards and regulations for telecommunications and information and communication technologies.

The OSI model was developed by the ISO (International Organization for Standardization) with the ITU-T (International Telecommunication Union).

Full form of ITU-T is International Telecommunication Union-Telecommunication .

It doesn't need deciphering. It's published. It was updated a few years ago by the ITU-T (International Telecommunications Union - Telecommunications Standardization sector) to add the code for the @ sign.

1)H.323 which is recommended by the ITU Telecommunication Standardization Sector (ITU-T) which is also incorporates signaling protocols, TCP-based Q.931 and H.245 for call control and registration admission status (RAS) for controlling user access.

2) Session initiation protocol (SIP)

3) IETF

4) TRIP and ENUM

for full details plz search google or website of "cisco"