Century Link has given the state an explanation for the 9-1-1 service outage earlier this month. 4,500 emergency calls did not go through during the outage, which hit most of the state.
In a report to the state, Century Link says the 9-1-1 phone service flat-lined because of trouble at a call center in Colorado.
But a fail-safe was expected to kick in, says Washington's Utilities and Transportation Commission.
Bill Weinman, the commission's assistant director of telecommunication, says calls should have been sent to a backup center in Miami.
"Obviously that didn't happen," said Weinman. "What are they doing to make sure they have processes in place that ensure that they are taking care of issues before they become major issues?"
Century Link says the Colorado company choked on the 9-1-1 calls because it ran out of digital tickets - a sort of name tag for each call.
Without the name tags, the calls didn't get to Miami.
CenturyLink says the call center has expanded the number of tickets, and it is looking at a fix for the fail-safe system.
The state's utilities commission says it is continuing its investigation.
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