(2014) Coding error knocked out 911 service for millions

From a Verge article:

For hours on an April day in 2014, 6,600 emergency calls from people in seven US states didn’t reach responders. The 911 outage affected 11 million people; in Washington state, every single person was affected. And in a new report investigating the causes of the outage, the FCC found this: “It could have been prevented. But it was not.”

Essentially, the coding error caused the system to stop giving unique IDs to 911 callers, and instead began counting them, one after the other, in one large set. When the set reached its pre-determined limit, the calls stopped coming through. Intrado’s system, because of the coding error, failed to realize there was a widespread problem.

via Are We Really Engineers? • Hillel Wayne