The+Telephone

The telephone, colloquially referred to as a phone, is a telecommunications device that transmits and receives sounds, usually the human voice. Telephones are a point-to-point communication system whose most basic function is to allow two people separated by large distances to talk to each other. Developed around the 1870s by Alexander Graham Bell and others, the telephone has long been considered indispensable to businesses, households and governments, is now one of the most common appliances in the developed world. The word "telephone" has been adapted to many languages and is now recognized around the world.

All telephones have a microphone to speak into, an earphone which reproduces the voice of the other person, a ringer which makes a sound to alert the owner when a call is coming in, and a keypad to enter the telephone number of the telephone to be called. The microphone and earphone are usually built into a handset which is held up to the face to talk. The keypad may be part of the handset or of a base unit to which the handset would be connected. A landline telephone is connected by a pair of wires to the telephone network, while a mobile phone or cell phone is portable and communicates with the telephone network by radio. A cordless telephone has a portable handset which communicates by radio with a base station connected by wire to the telephone network, and can only be used within a limited range of the base station.

The microphone converts the sound waves to electrical signals and then these are sent through the telephone network to the other phone and there converted by an earphone back into sound waves. Telephones are a duplex communications medium, meaning they allow the people on both ends to talk simultaneously. The telephone network, consisting of a worldwide net of telephone lines, fiberoptic cables, microwave transmission, cellular networks, communications satellites, and undersea telephone cables connected by switching centers, allows any telephone in the world to communicate with any other. Each telephone line has an identifying number called its telephone number. To initiate a telephone call the user enters the other telephone's number into a numeric keypad on the phone. Graphic symbols used to designate telephone service or phone-related information in print, signage, and other media include.



This Man is the inventor of the Telephone : Antonio Meucci