I'm really old, so it was in the mid to late 1980s, for work, and I'm struggling to remember the details. I had a Tandy device that fitted over the handset of a landline phone, you dialled the number and the data (from an electronic word processor) went chirping down the line. I once had to do it in a public phone booth, that was fun. Several times I was in a hotel room and had to ring reception first to explain I was going to make a data call, and please not to interrupt it.