36 years ago, on January 15, 1990, a software bug in the 4ESS switch triggered a cascade of failures that took down most of the AT&T long distance telephone network for about nine hours.
It was treated as a national crisis. There were investigations and task forces, both internal and external, and detailed findings were published and scrutinized. The case is still studied today in networking and software engineering courses.
Today's national T-Mobile failure will be forgotten by next week.
