I once visited one of those Strowger relay exchanges, but it was in the middle of the day, and it was clacking away like crazy. (Analog phone lines would compl

I once visited one of those Strowger relay exchanges, but it was in the middle of the day, and it was clacking away like crazy. (Analog phone lines would complete a physical circuit between two phones - hence "circuit switching". With digital, we moved to "packet switching" - bundles of bits with headers, etc.)