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RTTY (Radio Teletype) is a method of transmitting text message by radio. Data is usually sent using the 5 bit Baudot code, although ASCII is rarely used. Much military RTTY traffic is encrypted, using methods such as KG-84. Radioteletype (RTTY) is referred to as RATT or just "teletype" by military radio operators and in military radio manuals/publications.

Baudot RTTY is typically only used by ham radio operators and for transmitting public information such as weather reports and forecasts. The days of using RTTY to send news/press reports, etc are long gone.