Aurora and Douglas County are the latest governments to implement new reverse 911 emergency notification systems designed to alert residents on their cell phones and other devices, including land lines.

The changes reflect an effort by those communities to keep pace with the technology most people are now using to communicate.

Increasingly, residents are ditching traditional land line phones and using their cell phones as their primary number. So, emergency responders have developed ways to alert cell- phone users of, for example, a threatening storm or major police action - an effort called reverse 911.

"Only 25 percent of the 911 calls received are from land lines," said Mike Bedwell, manager of the Aurora Communication Center. "To have an effective reverse 911 system we have to have a way to communicate with everyone."

Aurora announced its new system Tuesday. Previously, Aurora could only notify land line users of an emergency.

Douglas County launched its global emergency notification system Feb. 1.

"We have a commitment to our citizens to protect them from any danger that threatens our community," said Cory Friend, communications manager for the Douglas County Sheriff's Office.

"The ability to reach all residents quickly during an emergency to warn them and provide guidance is critical to upholding that commitment."

In both Douglas County and Aurora, residents with land lines will still receive alerts. But people can opt to receive a notification via cell phone, e-mail, text message and more.

"We can isolate an area," Bedwell said. "If a SWAT operation is at Johnny Bad Guy's house, then we'll send a message to everyone in the neighborhood except to Johnny Bad Guy."

Aurora, which spent $150,000 for a software upgrade, envisions using the notification system to spread the word about road closures, construction delays and citywide events, as well as emergencies.

Douglas County reserves its system for emergencies only.

Both jurisdictions joined El Paso and Teller counties, both of which upgraded their 911 systems in 2007 to allow residents to register cell-phone numbers and e-mail addresses with the El Paso-Teller County E-911 Authority.

But only 6,700 residents have done that.

"That's a drop in the bucket when you think about the fact there are a quarter-million cell phones in El Paso and Teller counties," said Ben Bills, a spokesman for the E-911 Authority.

Bills also cautioned that the technology is only used to place outbound 911 calls to the public for safety reasons.

"Even though we can call their cell phone in an emergency, it doesn't mean, when they call 911, we will know where they're at," he said. "The technology isn't there yet."

How to sign up for emergency alerts

* Aurora: Go to auroragov.org and click on the emergency citizen notification link on the lower right of the home page.

* Douglas County: Go to dcsheriff.net and click on the emergency mass notification link.