You could definitely send telegraphs overseas, and sending or receiving them required no training.
and sending or receiving them required no training.
If you mean paying someone to send them, then sure. But it required learning Morse code, and learning to use a keyer.
You couldn’t send them overseas until after the invention of radio. Before that the signal traveled along a wire they laid the transatlantic cable.
The first transatlantic telegraph cable was laid down in 1854 and radio waves weren’t even theorized until 1873… https://en.wikipedia.org/wiki/Transatlantic_telegraph_cable