How Wireless Emergency Alerts Reach Mobile Phones
Few things interrupt an afternoon the way an emergency alert does. The tone cuts in, the phone shakes, and a few lines of text tell you why. Behind those lines sits a system with several owners and a long list of conditions attached.
Wireless Emergency Alerts (WEA) are free, text-like emergency messages, geographically targeted to mobile devices. Authorized public safety officials send them through the Federal Emergency Management Agency’s Integrated Public Alert and Warning System (IPAWS) to participating wireless carriers, which push them to compatible devices in the affected area. Participating carriers may let subscribers block all but National Alerts.
Who Sends an Alert and the Path It Takes
The Federal Communications Commission (FCC) describes WEA as a public/private partnership between FEMA, the FCC, and the United States wireless industry. The Warning, Alert and Response Network (WARN) Act established WEA in 2008, and the service became operational in 2012. The same law directed the FCC to adopt technical and operational requirements for it.
Carriers that participate must adhere to the FCC’s WEA rules. Carrier participation is widespread but voluntary. Wireless companies choose to take part, and the FCC requires every carrier that does not participate to notify its customers.
Authorized national, state or local government authorities send alerts about public safety emergencies, such as severe weather, missing children, or the need to evacuate. Other federal agencies originate alerts too, the National Weather Service among them. FEMA’s list runs wider: authorized federal, state, local, tribal and territorial public alerting authorities.
The FCC does not send alerts.
Alerts are free, and customers do not need to sign up to receive them.
Wireless providers primarily use cell broadcast technology to deliver WEA messages. Many providers have chosen a technology that is separate and different from voice calls and SMS text messages. A WEA can reach a mobile device without the need to download an app or subscribe to a service.
The alerts are not affected by network congestion. WEA is not designed to track, and does not track, the location of anyone receiving an alert. Should the IPAWS connection to wireless providers ever be interrupted, PBS WARN provides a backup method for sending WEAs.
Five Alert Types and Which Ones May Be Turned Off
The FCC lists five alert types that a WEA-capable device must receive and display. A device marketed as “WEA-capable” must support all WEA functions the FCC currently requires.
| Alert type | What it is | Can a subscriber opt out? |
|---|---|---|
| National Alert | A national or regional alert issued by the President, his designee, or the Federal Emergency Management Agency (FEMA) | No. Consumers cannot block National Alerts. |
| Imminent Threat Alert | An alert that requires fast action to protect yourself from a severe threat to life or property that is ongoing or likely to occur | Yes. Subscribers may opt out. |
| Child Abduction Emergency/AMBER Alert | An alert regarding a missing or abducted child | Yes. Subscribers may opt out. |
| Public Safety Message | An advisory that provides one or more actions that you can take to save lives or safeguard property during an emergency | Yes. Subscribers may opt out. |
| State/Local WEA Test | Tests to ensure that WEA is functioning properly | Not received by default. Subscribers can opt in. |
Source: Federal Communications Commission
Three of the five are optional on the receiving end: Imminent Threat Alerts, Child Abduction Emergency/AMBER Alerts, and Public Safety Messages. National Alerts are not; consumers cannot block them.
In passing the WARN Act, Congress allowed participating wireless carriers to offer subscribers the capability to block all WEAs except National Alerts. Test messages work the opposite way, staying off until a subscriber opts in through the device’s settings. FEMA says the opt-in and opt-out menu typically sits within the notification settings.
What Arrives on the Phone
The FCC says an alert appears on the handset’s screen as a text-like message, up to 360 characters long.
It arrives with a unique attention signal and vibration, which is particularly helpful to people with hearing or vision-related disabilities. FEMA says WEAs have a unique tone and vibration, both repeated twice.
Inside the message are the type and time of the alert, any action to take, and the agency issuing it. An alert may also carry a phone number or a website link, which a WEA-capable device can dial or open with a simple tap.
Language follows the phone. A device set to English receives WEA messages only in English. A device set to Spanish also receives WEA messages sent in Spanish.
A WEA-capable device stores an alert for at least 24 hours, or until the user deletes it. An incoming WEA will not interrupt an active call, so the caller can continue to communicate with 911 or take other protective actions. WEA messages also do not count toward texting limits on a wireless plan.
Older mobile devices not marketed as “WEA capable” may still be able to receive an alert through WEA. They may lack some or all of the features a WEA-capable device has.
Why One Phone Gets an Alert and Another Does Not
Two people stand on the same corner. One phone sounds. The other stays quiet.
The FCC lists the conditions. A handset must be WEA-capable, switched on, and not on “airplane mode.” It must also be in the vicinity of, and receiving service from, a cell tower of a wireless carrier that participates in WEA.
Some carriers may offer WEA over all or parts of their service areas, or over all or only some of their devices. Others may not offer it at all.
In a service area where the provider is not offering WEA, a WEA-enabled device would not receive alerts. The same holds while roaming on a provider network that does not support the service. Consumers with prepaid phones can receive WEAs as long as their provider has decided to participate and the customer has a WEA-enabled device.
Alerts are broadcast to the geographic area affected by an emergency. WEA-capable devices in that zone can receive the alert, even while roaming or visiting from another state.
WEA geographic precision is continuously improving. When the program launched, participating wireless providers were generally required to send alerts to an area no larger than the county or counties affected.
Beginning in 2017, participating wireless providers were required to send alerts to an area that best approximated the area affected. That applied even if the area was smaller than a county.
As of December 2019, participating providers must deliver alerts to technologically compatible phones in the area the alert originator specifies. Any overshoot must be no more than 1/10 of a mile.
This “enhanced geotargeting” relies on new smartphone technology and will be increasingly available as consumers upgrade their devices. WEA-compatible phones that do not support enhanced geotargeting will still receive alerts based on the 2017 geographic area requirements.
FEMA says WEAs are based on location. A WEA-capable phone receives one even in an area where its owner does not live, or outside the area where the phone is registered. A WEA-capable device that enters an area after an alert was sent will receive it, if the alert is still active.
When one person nearby receives a WEA and another does not, it may be due to inadequate cell reception. Other possible reasons include a phone set to “off” or “airplane mode,” or one not connected to a cell site broadcasting the alert. A cell site that is not broadcasting the alert, is undergoing maintenance, or is out of service may also be the cause.
A phone connected to a Virtual Private Network (VPN), or one opted out of alerts, may not receive an alert either. Sometimes a device gets stuck in a loop, alerting again and again for the same WEA. When that happens, it is most likely an issue with the device.
The Nationwide Test and Mobile Phones
At approximately 2:20 p.m. Eastern Time on Tuesday, November 17, 2026, FEMA, in coordination with the FCC, will conduct a nationwide test of the Emergency Alert System (EAS). The EAS is a national public warning system that requires radio, television, cable, satellite, and wireline video providers to deliver emergency alerts to the public.
Under the IPAWS Modernization Act of 2015, FEMA is required to conduct nationwide tests of public alert and warning capabilities. The law requires them at least once every three years.
Wireless Emergency Alerts were tested in 2023, but they will not be part of the 2026 nationwide test. Individuals will not receive Wireless Emergency Alerts on their phones as part of this test.
Normal programming may be briefly interrupted on radio and television stations, and the interruption is expected to last about one minute. If an actual emergency or significant weather event occurs on test day, FEMA and the FCC may postpone the test. The backup date is December 3, 2026.
So the November test travels through radio, television, cable, satellite, and wireline video providers. The alerts that reach phones were tested in 2023.