CenturyLink has given Washington state investigators an explanation for the six-hour 911 service outage earlier this month that prevented 4,500 emergency calls from getting through.
In a report filed with Washington's Utilities and Transportation Commission, the company says the calls got stuck at a routing center in Colorado.
Calls coming in are supposed to be assigned a digital ticket — a unique identifier that allows it to be routed to the right dispatchers.
But on the April 10 outage day, the Colorado call center had exhausted its supply of digital tickets. At that point, said the commission, the state expected that a failsafe would kick in so that calls would be routed to a backup center in Miami.
"Obviously that didn't happen," said Bill Weinman, the commission's assistant director of telecommunication. In fact, CenturyLink said the system was not designed to forward calls to Miami when a failure at such a preliminary stage occurred.
However, Century Link said the Colorado company Intrado won't run out of digital tickets again. Intrado has since greatly expanded the number of tickets available.
The state said it will ask for data about the incident from the companies involved as part of its continuing investigation.
