Western Electric 1A2 key telephone system, with Seriss Corporation 1A2 KSU

A look at an early key telephone system, and the modern homebrew key service unit that drives this one. Relevant links: http://seriss.com/1a2-ksu/ http://seriss.com/people/erco/1a2/ Greg Ercolano's YouTube channel, where he's posted a few videos of the 1A2 KSU and how it has evolved over time: https://www.youtube.com/channel/UCxHid9oBBg5lJ4TL2fu0Y7g A video of an original Western Electric 1A2 KSU working: https://www.youtube.com/watch?v=-7AMBA4-PbA