Number 1 electronic switching system
Quick Summary
The No. 1 Electronic Switching System (ESS), introduced by AT&T in 1965, revolutionized telephone networks by transitioning from electromechanical switches to electronic components. This innovation was driven by the increasing volume of telephone traffic and the demand for new services.1
The No. 1 ESS utilized a special "fereed" switch, which incorporated a magnetic alloy that allowed the switch to retain its state, acting as a memory. This system, along with advancements in memory devices, enabled the No. 1 ESS to handle up to 65,000 voice circuits and hundreds of new features. Subsequent revisions incorporated semiconductor memory, further enhancing its capabilities. This shift to electronic switching marked a significant departure from earlier electromechanical systems like the Strowger switch and crossbar systems.12
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