Telephone, from Greek: τ? λε(tēle, meaning "far") and φ ω ν? (ph not nē, meaning "sound") is a kind of remote communication equipment that can send and receive sound.
As early as the eighteenth century, the word "telephone" was used in Europe to refer to a microphone made of string. Its principle is that speech is a compound vibration in the air, which can be transmitted to solids and to conductive metals through electric pulses.
Extended data
Classification of telephone sets
(1) wired telephone
The telephone has the function of converting the sound wave of the terminal into an electronic signal, transmitting it to a distant party through a telephone line, regenerating the electronic signal transmitted by the other party into voice (sound wave), making it talk, and sending a signal (dialing pulse) selectable from multiple parties to inform the other party of the calling sound.
(2) wireless telephone
Wireless phones include analog cordless phones, digital cordless phones with telephone mother and child machines, mobile phones, PHS, etc.
(3) Smart phones
In addition to the complete fixed telephone function, smart phones usually have the functions of large-capacity business card management, incoming and outgoing call management, prevention of telephone harassment (telephone firewall), telephone business card management of enterprise groups (internal business cards), and many other functions to assist office work.
Baidu encyclopedia-telephone
Baidu encyclopedia-telephone