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.
- www.quora.com/How-is-a-voice-transmitted-from-one-phone-to-another
- www.quora.com/How-many-wires-does-a-telephone-use/answer/Peter-Yardley-1
Basic analogue phones connected to the public exchange use two wires mainly arranged as a twisted pair to reduce noise. The voice signal is differential (the voltage in one wire equal and opposite to the other) biased above ground by 48V. Using a twisted pair reduces induced noise because the noise signal will induce an equal voltage in each wire and because the signal is transmitted as the difference the effect of the induced noise will be dramatically reduced.
Phone Intercom by Make (2014)
Source. This video illustrates will the incredible simplicity of the connection of a telephone system. Compare that to the relative complexity of wireless communication, which requires modulation. Articles by others on the same topic
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.