 Telephone

We are at a point in history where the electrical telegraph is well established.

But people don't want to press letters one by one on a switch. They want to talk!

The first phones appear to have used telegraph lines directly.

Also wired phones don't require modulation, which likely made their development much easier than wireless voice transmission. You just send the signal as a voltage differential directly obtained from the air pressure: how the telephone works.

A telephone is an electronic device that allows for the transmission of voice or data between two or more people over a distance. The basic principle of a telephone involves converting sound waves (like those produced by a speaker's voice) into electrical signals, which can then be sent over a network (such as telephone lines, fiber optic cables, or wireless signals) to a receiver. The receiving telephone converts these electrical signals back into sound waves, allowing the recipient to hear the original voice.