After several years of development, the Commercial Mobile Alert System (CMAS) has been activated, allowing public safety authorities to send alerts to cell phone users anywhere, anytime—without the need for customers to opt in. Not since the Emergency Broadcast System in the 1960s has there been such a broad alerting initiative in the U.S.

The new system, also known as Wireless Emergency Alerts (WEAs), is a joint effort of wireless carries, FEMA, and the FCC. It has the potential to save lives and represents a fundamental shift in how our increasingly mobile public is alerted to emergencies.

How It Works

WEAs will be distributed to the public via Cell Broadcast (CB) technology. Unlike Short Message Service (SMS), which sends text messages back and forth between your device and other devices of your choosing, CB technology uses a cell tower in a particular location to “broadcast” a message to all the phones within range of the tower. Think of it like a radio broadcast for cell phones. Much like a radio can tune in and receive the signal from a particular station, a CMAS/WEA-equipped cell phone is always “tuned in” to receive messages.

In the event of an emergency, an authorized alerting agency can select a geographic area to broadcast a WEA. In order to receive the message, a person must be within range of cell towers within the area, and must have a phone capable of “hearing” the broadcast. Most cellular devices manufactured after mid-2011 have this capability, but users should check with their carrier to verify whether a device will receive a WEA message.

It is through use of CB technology that CMAS is able to provide geographic targeting without need for the public to sign up to receive the alerts. However, it is important to note that because WEAs are “broadcast” from towers, the geo-targeting feature is not as precise as GPS. GPS is a two-way street of communication between a GPS-equipped device and various positioning satellites. WEAs are not two-way. Just like a radio station broadcasts in one direction, WEAs are also broadcast in one direction; out. The broadcasting towers have no way of knowing specifically who has received their message, nor can the public reply to the message. It is simply a modern-day “shout” to give a heads-up that something requires your attention.

System Limitations

Although the system is live, not everyone will receive WEAs immediately. There are still steps to be taken before the system is fully utilized. Local and state authorities must complete a four-step process to register with FEMA as “alerting authorities.” A few organizations have already completed the process, which was unveiled only a few weeks ago, however the National Weather Service intends to start using WEAs very soon.

Additionally mobile devices must be equipped by the manufacturers to receive WEAs. It’s unclear how many WEA-equipped devices are in consumers’ hands, but Sprint has stated it has several million WEA-equipped devices in the field already. Other carriers have been equipping their devices to handle WEAs, too.

Another limitation is usage and the amount of information that can be relayed. WEAs will only be sent for three purposes: imminent threats, AMBER alerts and presidential messages during national emergencies. Alerts are limited to a maximum of 90 characters and at this time cannot include website addresses.

After waiting for some time, the system is ready. Yes, it will still take some time for CMAS/WEA alerts to become commonplace and well-known. Undoubtedly, glitches will occur. But as alerting authorities and wireless customers become aware of the program, hopes are high that it will improve public safety and add yet another useful application to wireless technology.

Rick Wimberly is president of Galain Solutions Inc., the world’s leading independent consultancy on alert and warning practices and technologies. A resource for public safety agencies, corporations and educational institutions, Galain Solutions does not sell notification systems, but instead helps clients select technologies and successfully implement notification programs. Visit for more information.


Posted by Janine E. Mooney, Editor

May 03, 2012