Keyfax was the US version of the British Ceefax teletext. It was launched in 1982 but was shut down already by 1984, partly due to problems with getting the British teletext decoders approved in USA. Instead, Keyfax became a videotex service in Chicago and changed from the British standard to the American NAPLPS. But that failed too and Keyfax went bust in 1986. More info.
Post updated in 2024.