How Emergency Notifications Work

By: Dave Roos
Mass alert systems warn people of incoming storms. See more pictures of storms.

Technology keeps us informed and in touch like never before. Think about the technology we use every day compared to 20 years ago: e-mail, instant messaging, pocket cell phones, SMS (text) messaging, PDAs. . .the list goes on. We already know this technology can increase connectivity and productivity, but did you know they can also save lives during an emergency?

In this article, we will talk about emergency not­ifications, defined as any message -- delivered over any device or platform -- intended to warn large groups of people about impending or existing danger.


Poor communication is often to blame for turning an emergency into a catastrophe. Think of the confusion and communication breakdowns that plagued emergency workers during the World Trade Center attacks. Or a 2003 California wildfire where 17 people died because firefighters had to go door-to-door telling residents to evacuate.

In recent years, an entire industry has emerged to fill the communication gaps created by natural and manmade emergencies. These "mass notification" or "emergency notification" services offer everything from powerful outdoor broadcasting systems to automated electronic notifications sent via e-mail, cell phones and PDAs.

Corporations are signing up with these subscription services to fulfill new federal requirements for disaster recovery plans. Schools and colleges are safeguarding students and reassuring parents with campus-wide alert systems. Municipalities are offering automated emergency alerts that citizens can opt to receive via e-mail, phone or text message.

In this article, we're going to divide emergency notifications into two general categories: non-discriminating warnings and targeted alerts. Read on to learn more about how non-discriminating emergency notifications work.


Non-Discriminating Alarms

An air raid siren can be heard for miles
Courtesy Oak Ridge National Laboratory Emergency Management Center

An air raid siren is the best example of a non-discriminating emergency notification. The siren's warning tone or audio message is delivered to everyone within audible range of the broadcast, no matter who they are or what equipment they own. All other types of warnings rely on communications devices such as televisions, radios, phone, computers or handhelds, to deliver a message.

Unlike targeted warnings, an air-raid siren is designed to reach a broad swath of the population, not just those most likely to be affected by the emergency.


"Air-raid siren" is really a misnomer. Very few long-range warning systems are still used for the express purpose of alerting citizens to a military attack. Some common applications of modern warning sirens include:

  • Volunteer fire calls
  • Severe storm warnings
  • Tornado warnings
  • Hurricane warnings
  • Tsunami warnings
  • Dam failure alerts
  • Chemical spill alerts

Many modern warning sirens begin with a tone or series of tones, then play a recorded message, often encouraging citizens to turn on their televisions or radios for further instructions. Those TV and radio broadcasts are part of another non-discriminating warning called the Emergency Alert System (EAS).

The EAS, formerly known as the Emergency Broadcast System, was created by the Federal Communications Commission (FCC) as a way for the president to speak to the country in a time of crisis. In 1963, state and local emergency officials were also permitted to use to the warning system, which now broadcasts over all TV and radio networks, including air, cable, satellite and digital channels.

Messages from the EAS are slightly more targeted than warning sirens, because state and local officials can choose over which stations to broadcast their message based on the areas most affected by the emergency. The EAS also teams with the National Weather Service to provide real-time storm and severe weather information to participating stations. The messages can even be broadcast in Spanish to Spanish-language stations in the U.S.

The FCC is looking into expanding the system to "take full advantage of digital and other emerging communications technologies." Private companies are competing to corner the emergency notification market. Click on the next page to read more about these highly targeted emergency notifications.


Targeted Emergency Notifications

Alerts can be sent directly to cell phones.

The simplest example of a targeted emergency notification system is a phone tree. Phone trees are an effective way to quickly contact a small to medium-size group of people (less than 100). Phone trees are considered a targeted notification because only the specific people who are affected by the emergency are called. Here's how phone trees work:

  1. The organizer makes a list of all the members of the phone tree, including all pertinent contact information.
  2. Employees use the Web portal or software to add individual contact information to the database, including phone and fax numbers and e-mail addresses.
  3. The organizer assigns each key member a small group of people to call (not more than 10).
  4. In an emergency, the organizer calls the key members with a scripted message.
  5. The key members relay the message to everyone on their call list until receipt of the message is confirmed. If someone cannot be contacted after a predetermined amount of time, the key member informs the organizer.

Phone trees have limitations:


  • If one or more key members can't be reached, that shifts the responsibility back to the organizer or other key members, who may not be able to make all the calls in time.
  • The larger the group, the greater the likelihood that one or more of the key members will not be available.
  • Phone trees are limited because they rely exclusively on one means of communication. The ability to send messages over multiple platforms is a chief advantage of automated electronic notification systems, which we'll talk about next.

Many companies offer mass notification and emergency notification services. These services are basically powerful, automated phone trees. They can simultaneously send an emergency alert to thousands of people over all available communications platforms: e-mail, phone, cell phone, SMS, pager, PDA and fax.

Most mass notification services are subscription-based, which means that all the software and hardware necessary to run the system is housed off-site. Clients access the system through a desktop Web portal or a simple desktop API (application programming interface). Here's how a typical subscription mass notification system works:

  1. Employees of the company or organization access the electronic notification system through a Web portal or simple software interface on their desktop.
  2. Employees use the Web portal or software to add individual contact information to the database, including phone and fax numbers, e-mail address and SMS.
  3. The Web portal or software allows users to organize contacts into an unlimited number of groups and subgroups. Most allow you to upload contacts and groups from existing e-mail programs like Microsoft Outlook. (Some electronic notification systems suggest that companies delegate authority to certain users only for contacting the largest groups.)
  4. When it's time to initiate a notification, users log onto the Web portal or access the system by phone.
  5. Users then choose over which platforms they'd like to send their message. Most electronic notification services include text-to-speech capability so a written message can also be sent as audio to phones.
  6. Once the message is typed or recorded and sent, it arrives at the off-site headquarters of the electronic notifications service, where servers instantly send the message off to five or 500,000 recipients.

There are many potential applications for automated emergency notifications:

  • Severe weather
  • Wildfire/earthquake/tsunami/flood
  • Terrorist attack
  • Industrial accident
  • Child abduction
  • Dangerous persons in the area

Many municipalities and townships contract with mass notification services to keep citizens informed of emergencies. Washington D.C., for example, has a system in which citizens can sign up to receive emergency alerts by e-mail, SMS and cell phone.

These systems can also be linked with geographical data to create highly targeted and effective messages. Mass notification company 3n has a product called the InstaCom GIS system that allows municipal emergency workers and law enforcement officials to target messages using a GPS map interface. Officials can send alerts to residents living in a certain zip code or contact homes within a certain radius of an emergency.

These geographically based systems are especially effective for warning citizens in the event of a localized gas leak, chemical spill, child abduction, or even a prison escape.

Here are some of the features and advantages of automated mass notification systems:

  • Saves precious time in an emergency by contacting all constituents simultaneously
  • Frees up emergency workers and employees to concentrate on other tasks
  • Improves chances that the message is received by contacting recipients over all available communications platforms
  • Messages can be sent by Web or by phone, ensuring that critical alerts can still be sent even when there is no Internet connection
  • Ability to track and confirm receipt of message in real time
  • Some notification systems stop contacting members after a certain number, particularly helpful when a volunteers are needed quickly
  • Ability to record messages and leave them on a virtual bulletin board accessible by employees or constituents through a special 800 number and PIN

Read on to find out more about emergency notifications and the technology that powers them.