Originally used for transmitting Vietnamese text over telex systems, it is one of the most used input method on phones and touchscreens and also computers.
Telex services at the time ran over infrastructure that was designed overseas to handle only a basic Latin alphabet, so a message reading "vỡ đê" ("the dam broke") could easily be misinterpreted as "vợ đẻ" ("the wife is giving birth").
Nguyễn Văn Vĩnh, a prominent journalist and translator, is credited with devising the original set of rules for telex systems.
By contrast, a byte-oriented code page like VISCII takes up only one byte per Vietnamese character but requires specialized software or hardware for input.
In the 2000s, Unicode largely supplanted language-specific encodings on modern computer systems and the Internet, limiting Telex's use in text storage and transmission.
Since the letters f, w, z, and j do not exist in Vietnamese, Telex assigns diacritics to their corresponding keys, allowing users to type màn as mafn.