What is the telephone unit?

Before there was a mobile phone, the telephone generally referred to the landline, and its quantitative unit (quantifier) used to be "Taiwan" or "Department". Nowadays, mobile phones are also called telephones, and most people call them "A". Example: I installed a landline and bought a mobile phone.

Telephone 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 strung together with wires (a cup strung together with wires) The telephone was attributed to Alexander Graham Bell. The principle of the early telephone is that sound is a compound vibration in the air.

It can be conducted to solid or conductive metal by electric pulse. Bell applied for the telephone patent in March 1876.

The improvements and inventions of telephone in history include: toner microphone, manual switchboard, dial, automatic telephone exchange, program-controlled telephone exchange, dual-tone multi-frequency dialing, voice digital sampling and so on. In recent years, new technologies include ISDN, DSL, VoIP, analog mobile phone and digital mobile phone.