T.50 (standard)

ITU-T recommendation T.50 specifies the International Reference Alphabet (IRA), formerly International Alphabet No. 5 (IA5), a character encoding. ASCII is the U.S. variant of that character set.

The original version from November 1988 corresponds to ISO 646. The current version is from September 1992.

History

At the beginning was the International Telegraph Alphabet No. 2 (ITA2), a five-bit code. IA5 is an improvement, based on seven-bit bytes.

Recommendation V.3 IA5 (1968): Initial version, superseded<ref name="Salste_2016"/><ref name="ITU-CCITT_T50_1988"/>
Recommendation V.3 IA5 (1972): Superseded<ref name="Salste_2016"/><ref name="ITU-CCITT_T50_1988"/>
Recommendation V.3 IA5 (1976-10): Superseded
Recommendation V.3 IA5 (1980-11): Superseded
Recommendation T.50 IA5 (1984-10): Superseded<ref name="ITU-CCITT_T50_1988"/>
Recommendation T.50 IA5 (1988-11-25): Superseded<ref name="Salste_2016"/><ref name="ITU-CCITT_T50_1988">Template:Citation</ref>
Recommendation T.50 IRA (1992-09-18): In force<ref name="Salste_2016">{{#invoke:citation/CS1|citation

|CitationClass=web }}</ref><ref name="ITU-CCITT_T50_1993">Template:Citation</ref>

Use

This standard is referenced by other standards such as RFC 3939 ("Calling Line Identification for Voice Mail Messages"). It is also used by some analog modems such as Cisco ones.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>