Phone

"Phone" redirects here. For other uses, see Telephone (disambiguation).
For other uses, see Telephone (disambiguation).

An Olivetti dial telephone, 1940

Phone, colloquially called 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 in the mid 1870 by Alexander Graham Bell and others, the phone has long been considered indispensable to businesses, households and governments, is today one of the most common appliances in the developed world. The word "telephone" has been adapted to many languages ​​and is now recognized worldwide.

All modern phones have a microphone to speak into, an earphone (or "speaker") which reproduces the voice of the other person, a ringer which makes a sound to alert the owner when a call is incoming, and keyboard (or on older phones a telephone) to enter the telephone number to call. 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 unit or a base unit to which the handset must be connected. A landline telephone is connected by a pair of son to the telephone network, and a mobile telephone (also known as a cell phone) is portable and communicates with the telephone network by the radio. A wireless phone is a handset unit which communicates by radio with the base station handset owners which is connected by wire to the telephone network, and may be used in approximately 50 feet from the base station.

The microphone converts sound waves to electrical signals, and then they are sent through the telephone network to the other phone and converted by an earphone or speaker, 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 network of telephone lines, fiber optic cables, microwave transmission, cellular networks, satellite communications and telephone cables submarine connected by switching centers, allows any phone in the world to communicate with others. Each telephone line has an identifying number called its telephone number. To initiate a call from the user enters the number of the other phone into a keypad on the phone. Graphic symbols used to designate telephone service or phone-related information in the press, posters, and other media include ℡ (U + 2121), ☎ (U + 260E), ☏ (U + 260F), and ✆ (U + 2706).
Although originally designed for voice communications simple, most modern phones have many additional features. They may be able to record voice messages, send and receive text messages, take and view photos or videos, listen to music and surf the Internet. A current trend is phones that integrate all communications and mobile computing needs, they are called smart phones.