Transferring information between far spaces across the world always meant a big challenge in the human history. There was some methods during the ancient times and the middle ages, like smoke signals, beacons or pigeon posts, but the speed and the reliability of the information transfer was not the most satisfactory.
The first big breakthroughs in the history of worldwide communication was the rapid spreading of the electrical telegraph networks starting from the middle of 19th century. By 1902, as the result of laying several submarine communication cables, the telegraph system encircled the world. After that, at the early 20th century, the telephone started to take the place of the telegraph, and by the end of the century, it has become one of the most popular communication device all around the world.
A kutatási beszámoló letölthető innen (PDF)