This in particular caught my eye, discretely buried in the (excellent) article: " And AT&T continued to improve the technology at work in its infrastructure. T

This in particular caught my eye, discretely buried in the (excellent) article: " And AT&T continued to improve the technology at work in its infrastructure. The transistor, invented at Bell Labs in 1947, eventually allowed for digital, solid-state switching technology to replace electromechanical switches. "