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This site is optimized for PC/Mac desktops and Tablets

You’ve found the perfect place to experience the golden age of electromechanical telephone exchanges! To appreciate this era, a hardware device was built for in-person interactive demos. This site recreates the hands-on experience with a virtual machine using video playback of the device under operation. Why Calling315? 

The demos include recorded dialog, relay operations, exchange switching sounds, classic telephone intercept recordings, exchange-themed music remixes and much more. There are 100+ pieces of audio media included with some explainer videos. 

Aside from the demos are many historical perspectives, essential inventions, and the anatomy of the foremost automatic exchanges as they advanced starting from 1879 until the 1960's. Fifteen exchange switch types are explained with more than 250 images/videos.   

Check out a hierarchical Table of Contents for an overview of the site.    

Press the play icon below for a short introduction. To run a demo, to go the
Demos page  

Interactive Telephone relay demo front panel

Tribute to Relays, Electromechanical exchanges, interactive demos

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