Telephone crossbar switch RVD 211, made by Swedish Ericsson, Sweden, 1970.
Crossbar switching dates back to the earliest days of manual telephone switchboards, which used sets of overlapping brass bars with holes at the intersections for brass plugs to connect telephone calls. The first true crossbar switches were developed in 1913 by an engineer at Western Electric in the United States. Over the years, many different companies developed their own version of crossbar switches. They were widely used across Europe and in Britain, particularly in the 1960s and 1970s.