> An ASCII artist who goes by the screen name “goto80” told me in an email that, according to his research, the first modern text-based porn was probably sent via teletext. Teletext was a late 70s pre-internet technology for sending text and graphics to a television set, that never quite took off in the way people thought it would at the time.
Also, I have seen ascii art on telex-type machines. These are limited by using only five bits, and so you can only use lowercase characters (or uppercase, but not both).
There are some examples here: http://artscene.textfiles.com/rtty/RTTYCOM/