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The historical telephone: A roadmap

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Thanks to modern telephony, connecting with anyone in the world is now instantaneous— but it wasn't always this way. This infographic takes you through the telephone's incredible journey, beginning with its invention in 1876, to what you use to make calls today.

Enjoyed this infographic? Check out the original Life of a call post by Switch co-founder and VP of Telephony which inspired this timeline: http://bit.ly/1Lb21QK

Publié dans : Périphériques & matériel
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The historical telephone: A roadmap

  1. 1. Part 01 / 03 switch.co http://bit.ly/1JUEh0m Source MARCH 1876 Alexander Graham Bell becomes the first to patent, widely disseminate,and develop telephone technology in the U.S. Alexander Bell spoke the first words transmitted through the telephone, “Mr. Watson, come here. I want to see you.” Numbers are mapped to digits, as seen on today’s dial pads. The network type for telephone communication changes from Bell’s original point-to-point “mesh network” (harder to maintain) to a “central exchange” (manually operated). 1950s The rotary dial phone and the mechanical switch eliminate the need for human operators. 5 1970s Analog to digital conversion of voice is invented Computer Scientist Vinton Cerf invents Transmission Control Protocol/Internet Protocol (TCP/IP), allowing computers to communicate with each other. MODERN TELEPHONY Signaling System (SS7) Links call information to caller. Common Channel Signaling (CCS) Pairs signaling channel and active voice channel. Dual Tone Multi Frequency (DTMF) Pressable phone numbers emit sine waves. 6 DIGITIZATION 8000 samples of the raw analog signal are transmitted over the Publicly Switched Telephone Network (PTSN) and interpreted by a computer chip. As the number of users grows, it quickly turns into a mesh network with way too many wires to build and maintain. The answer is a central exchange. Everyone connects with one line to the exchange. Operators at the first exchanges asked, “Number please,” before manually transferring calls from caller to call recipient. Life of a Call A HISTORY

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