A manufacturer of telephone call-routing computers said Tuesday that a defect in three or four lines of computer code, rather than a hacker or a computer ”virus,” appeared to be the culprit behind a mysterious spate of breakdowns that disrupted phone service for 10 million customers around the country in recent weeks.
In congressional testimony Tuesday, an official of the manufacturer, DSC Communications of Plano, Texas, said all the problems had been traced to its software, which had not been thoroughly tested for hidden ”bugs.”
The flaws caused the computers to send a flood of erroneous messages when the computer encountered routine problems. This flood of messages overwhelmed all other call-routing computers in the telephone network, making it impossible for most people in the affected areas to complete local calls.
The affected areas included Los Angeles, Washington, D.C., Virginia, Maryland, West Virginia, Pittsburgh and San Francisco.
