Preparing the history of telemedicine was like riding a rocket through human history. But first some clarification.
What is the difference between telehealth and telemedicine?
Very often both terms are used interchangeably. The HRSA (Health Resources and Services Administration) defines telemedicine as only about remote clinical services, whereas telehealth also includes non-clinical services. The WHO (World Health Organisation) includes all measures of healthcare in telehealth.
The history of telemedicine is also a history of human communication technology
Before the invention of writing, we had a mix of oral communication (including sending a messenger) and signals (fire and smoke). The advent of written communication added letters.
The first incident which would be regarded as telehealth was when A. G. Bell called his lab assistant to call his assistant for help when he spilled acid on his trousers. That was 1876—the beginning of the cable-based communication era dominated by the telephone and the telegraph.
Then came radio, microwave circuits, satellite communication and in the 90s the rise of the personal computer era.
Enough talking. Here is the infographics.