Tag: phones

A telephone , or phone, is a telecommunications device that permits two or more users to conduct a conversation when they are too far apart to be heard directly.

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. The telephone was the first device in history that enabled people to talk directly with each other across large distances.

The essential elements of a telephone are a microphone to speak into and an earphone 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 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.

The first telephones were directly connected to each other from one customer’s office or residence to another customer’s location. Being impractical beyond just a few customers, these systems were quickly replaced by manually operated centrally located switchboards.These exchanges were soon connected together, eventually forming an automated, worldwide public switched telephone network.For greater mobility, various radio systems were developed for transmission between mobile stations on ships and automobiles in the mid-20th century.