A magazine where the digital world meets the real world.
On the web
- Home
- Browse by date
- Browse by topic
- Enter the maze
- Follow our blog
- Follow us on Twitter
- Resources for teachers
- Subscribe
In print
What is cs4fn?
- About us
- Contact us
- Partners
- Privacy and cookies
- Copyright and contributions
- Links to other fun sites
- Complete our questionnaire, give us feedback
Search:
AT&T Crash, 1990
The day the phones stopped working...all of them.
In late 1989, AT&T engineers upgraded the software of their 114 US switching centres: the computers that make the connections so your phone links to the one you are calling. Each computer was duplicated so if one went wrong the other would take over. On January 15th 1990, they stopped working: 70 million calls failed. The problem was in a single line of code out of millions...and it was in both computers' copies. AT&T lost $1 billion as customers fled to their competitors.
