AT&T collapse:A single typo that shut down the US long-distance network

Posted by xthe on Friday January 16, 2026 @05:20PM
from the en.wikipedia.org dept.

https://en.wikipedia.org/wiki/1971_AT%26T_network_switching_system_collapse

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Re:AT&T collapse:A single typo that shut down the US long-di... by xthe on Friday January 16, 2026 @05:20PM (#46652992)

Incredible story: In 1971, a tiny bug in AT&T’s switching software caused a cascading failure that took down nearly all long-distance calling in the US. The entire system collapsed because one switch sent a malformed signal and every other switch copied the same failure. Wild early example of distributed-system fragility.

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Re:AT&T collapse:A single typo that shut down the US long-di... by bityard on Friday January 16, 2026 @06:07PM (#46653420)

I'll bet it is, but that link is a 404.

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Re:AT&T collapse:A single typo that shut down the US long-di... by slater on Friday January 16, 2026 @06:22PM (#46653524)

Yeh I can't find anything about this, only the outage in 1990:

https://users.csc.calpoly.edu/~jdalbey/SWE/Papers/att_collap...

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