Much earlier. Except that in most of the world they fell out of use before telephones became a common household item, so for people who grew up between, very roughly, the 60s and early 90s, mobile phones were the first phones with letters on them. We had heard about those strange phone "numbers" with letters in them via American television shows, of course.
Yep, apologies if I wasn't clear. I said "at least" since the late eighties and nineties since that's around when I first became coherent enough of a human to notice. I didn't intend it to be interpreted as "around" the eighties and nineties.
