#strowger-type

Normally I don’t post photo’s that aren’t my own, but I feel this illustrates a point very well.  What you’re looking at is a museum setup of a step-by-step telephone exchange.  These were probably taken from a small rural central office, and you can see it’s composed of Strowger mechanical switches. 

Strowger Step-by-Step Telephone Switch

This right here is the telephone switch that I’ve been trying to get my hands on for some time.  A Strowger SxS two-stage switch -- the first type of automatic switching equipment ever used for telephony.  The basic design dates back 125 years!

This here is a line finder module, designed to seek an empty line for a customer before they begin dialing.  As such, it contains 6 relays up top instead of 5 typically found on the intermediate selectors.  It also contains three levels of wipers instead of two.  This switch would require a bank of contacts in order to operate, which are kept separate for the purposes of modularity.