A telephone (derived from the greek τῆλε, tēle, “far” and φωνή, phōnē, “voice”, together meaning “distant voice”), or phone, is a elecommunications device that permits two or more users to conduct a conversation when they are too far apart to be heard directly. A telephone converts sound, typically and most efficiently the human voice nto electronic signals that are transmitted via cables and other communication channels to another telephone which reproduces the sound to the receiving user.

In 1876, Alexander Graham Bell was the first to be granted a United States patent for a device that produced clearly intelligible replication of the human voice. This instrument was further developed by many others. The telephone was the first device in history that enabled people to talk directly with each other across large distances. Telephones rapidly became indispensable to businesses, government and households.

The essential elements of a telephone are a microphone (transmitter) to speak into and an earphone (receiver) which reproduces the voice in a distant location. In addition, most telephones contain a ringer to announce an incoming telephone call, and a dial or keypad to enter a  telephone number when initiating a call to another telephone. The receiver and transmitter are usually built into a handset which is held up to the ear and mouth during conversation. The dial may be located either on the handset or on a base unit to which the handset is connected. The transmitter converts the sound waves to electrical signals which are sent through a telephone network to the receiving telephone, which converts the signals into audible sound in the receiver or sometimes a loudspeaker Telephones are duplex devices, meaning they permit transmission in both directions simultaneously. The essential elements of a telephone are a microphone (transmitter) to speak into and an earphone (receiver) which reproduces the voice in a distant location. In addition, most telephones contain a ringer to announce an incoming telephone call, and a dial or keypad to enter a  telephone number when initiating a call to another telephone. The receiver and transmitter are usually built into a handset which is held up to the ear and mouth during conversation. The dial may be located either on the handset or on a base unit to which the handset is connected. The transmitter converts the sound waves to electrical signals which are sent through a telephone network to the receiving telephone, which converts the signals into audible sound in the receiver or sometimes a loudspeaker Telephones are duplex devices, meaning they permit transmission in both directions simultaneously.