For mechanical devices, the symbol appeared on the keyboard of the Remington Standard typewriter (c. 1886), but was not used on the keyboards used for typesetting. It appeared in many of the early teleprinter codes and from there was copied to ASCII, which made it available on computers and thus caused many more uses to be found for the character. The symbol was introduced on the bottom right button of touch-tone keypads in 1968, but that button was not extensively used until the advent of large scale voicemail (PBX systems, etc.) in the early 1980s.