For 80 minutes Thursday night, 911 callers using a landline couldn't reach emergency dispatchers in Douglas County.
Instead, the 911 center received thousands of non-emergency calls that were misrouted, through a glitch that officials still were trying to understand Friday morning.
Instead of the 120 to 140 emergency calls an hour seen on a typical evening, operators were fielding 200 non-emergency calls per minute, said Mark Conrey, Douglas County 911 director.
“If you called last night, you got nothing. You got dead air,'' Conrey said about emergency callers in Douglas County.
“It was very intense, as we tried everything we could think of” to isolate the problem, he said. “Our operators were handling calls the best way they could.''
The problem was caused by a routing error linked back to regional long-distance calls handled by AT&T, Conrey said. The center couldn't receive emergency calls placed from landlines from about 9:20 p.m. to about 10:40 p.m. Mobile phone calls were received without trouble.
Conrey ruled out a deliberate attempt to create mayhem.
“This definitely was not a cyberattack,'' he said, “but this was a preview of what a cyberattack would look like.''
He said he had no idea how many calls the 911 center missed.
Normally, Conrey said, 911 center calls feed into one of about a half-dozen CenturyLink handling centers in the Omaha area. They are transferred to another operation in the Bluffs and then to Douglas County emergency dispatchers at 156th Street and West Maple Road, all in a split second.
Somehow, regional long-distance, non-emergency landline calls handled by AT&T and outside Douglas County's 911 system began pouring into the Douglas County 911 center, Conrey said.
“We were inundated with calls from all over the region,'' he said.
The region includes Nebraska, Iowa, North and South Dakota, Colorado and Utah.
Usually if callers to the Douglas County 911 center are unable to get through due to some error, he said, calls are automatically rolled to a backup line so nothing is missed.
Thursday night's routing error sent so many calls to Douglas County 911 that even the backup line malfunctioned, Conrey said.
He said he didn't know whether human error or computer error caused the AT&T routing glitch.
CenturyLink technicians spent about an hour determining that the error was not on their end, he said, and then began working with AT&T representatives to correct the regional routing error.
"We're looking into it," AT&T spokesman Mark Giga said Friday. He said he didn't have any details to share yet.
Douglas County Sheriff Tim Dunning said he was not aware of any missed calls for service during the outage.
Sarpy County 911 Director Larry Lavelle said his overnight staff reported no problems except for one call they couldn't transfer to Douglas County.
The Douglas County 911 center will continue to investigate the glitch, with the aim of preventing it from happening again, Conrey said.
“What can we learn from this?'' he asked. “We'll have to re-evaluate our age-old system'' to determine whether the center can handle a cyberattack.
Douglas County Administrator Patrick Bloomingdale agreed with Conrey, saying that if planning for 911 malfunctions wasn't on the county's radar, “it certainly is now.”
“We can take this as a learning opportunity to prepare,” he said. “What do we have in place now? What do we need to change?”
World-Herald staff writer Cody Winchester contributed to this article.