July 19, 2017

Understanding the Reverse 911 system

By Daniel Arens

Following a large grass fire south of Beulah, a reverse 911 call was sent out to residents in the southern part of town, warning of the fire and requesting a volunteer evacuation as a precautionary measure.
Thankfully, the fire was contained outside of city limits by local fire departments. However, the incident raised questions about how the reverse 911 warning process works.
Carmen Reed, Mercer County emergency manager and 911 coordinator, explained that there are two aspects to the system, one for landlines using voice messages and one for cell phones using text messages. The landline system uses the 911 database, which Reed updates periodically.
However, the cell phone process is a little more complicated, since cell phone numbers are not easily kept in a database. A federal reverse 911 system called the Integrated Emergency Notification System (IPAWS) is used instead.
In order to make contact with the ever-changing cell phones used in a given area, IPAWS sends the call out to all cell towers in the designated area, and the message is transmitted to cell phones within the range of the tower or towers. Because the system was designed and is operated federally, Reed explained that local responders cannot alter how the system works.
“The alert will have a high shrill sound and you can look at the message on your phone,” Reed said, “but once you try to open the phone the message goes away.”
The process means that any cell phones within the area, regardless of whether the person is actually from the region or just happens to be passing through, may receive the call.

The Weather Network