Wireless Emergency Alerts

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(Old) example of a CMAS test alert as shown on an Android phone.

Wireless Emergency Alerts (WEA, formerly known as the Commercial Mobile Alert System (CMAS), and prior to that as the Personal Localized Alerting Network (PLAN)),[1] is an alerting network in the United States designed to disseminate emergency alerts to mobile devices such as cell phones and pagers.


The Federal Communications Commission proposed and adopted the network structure, operational procedures and technical requirements in 2007 and 2008 in response to the Warning, Alert, and Response Network (WARN) Act passed by Congress in 2006, which allocated $106 million to fund the program.[2] CMAS will allow federal agencies to accept and aggregate alerts from the President of the United States, the National Weather Service (NWS) and emergency operations centers, and send the alerts to participating wireless providers who will distribute the alerts to their customers with compatible devices via Cell Broadcast, a technology similar to SMS text messages that simultaneously delivers messages to all phones using a cell tower instead of individual recipients.[3][4]

The government issues three types of alerts through this system:

  • Alerts issued by the President of the United States.
  • Alerts involving imminent threats to safety of life, issued in two different categories: extreme threats and severe threats
  • AMBER Alerts.[3]

When the alert is received, a sound is played if the ringer is on. On nearly all devices, the Emergency Broadcast System radio/TV attention signal sounds in a predetermined pattern.[5]

The system is a collaborative effort between the Federal Emergency Management Agency (FEMA), the Department of Homeland Security Science and Technology Directorate (DHS S&T), the Alliance for Telecommunications Industry Solutions (ATIS), and the Telecommunications Industry Association (TIA),[6]


Within ten months of FEMA making the government’s design specifications for this secure interface for message transfer available, wireless service providers choosing to participate in CMAS must begin development and testing of systems which will allow them to receive alerts from alert originators and distribute them to their customers.[7] Systems must be fully deployed within 28 months of the December 2009 adoption of such standards and are expected to be delivering alert messages to the public by 2012.[6] Although not mandatory, several wireless providers, including T-Mobile, AT&T, Sprint, and Verizon have announced their willingness to participate in the system.[2] Providers who do not wish to participate must notify their customers. Some phones which are not CMAS-capable may require only a software upgrade; while others may need to be replaced entirely.[3]

CMAS messages, although displayed similarly to SMS text messages, are always free and are routed through a separate service which will give them priority over voice and regular text messages in congested areas.[3] Customers who have the capability of receiving CMAS alerts (also known as PLAN[citation needed] and WEA) will be automatically signed up by their carrier.[8] If they do not want to participate they may opt to block most CMAS messages; however, CMAS regulations[9] prohibit participating carriers from configuring phones to allow users to opt out of messages issued by the President.[3]

Public television stations are also required by the FCC to act as a distribution system for CMAS alerts. Within 18 months of receiving funding from the Department of Commerce, all public television stations must be able to receive CMAS alerts from FEMA and transmit them to participating wireless service providers.[7]

On April 6, 2017, Canada's telecom regulator, the CRTC, ruled that all wireless carriers in Canada must begin relaying public alerts over LTE wireless networks by April 2018. Canada will use a variation of WEA backed by Pelmorex Media's National Alert Aggregation and Dissemination (NAAD) system.[10][11]

National Weather Service[edit]

The Commercial Mobile Alert System (CMAS), interface to the Wireless Emergency Alerts (WEA) service, went live in April 2012.[12] The NWS began delivering its Wireless Emergency Alerts on June 28, 2012.[13][14]

Warning types sent via CMAS include tornado, flash flood, dust storm, hurricane, typhoon, extreme wind, and tsunami warnings; severe thunderstorm warnings are not included due to their frequency in many areas of the United States. Also, until November 2013, blizzard and ice storm warnings were also included in CMAS; they were discontinued based on customer feedback[15] due to such warnings typically issued well in advance of approaching winter storms, thus not representing an immediate hazard. While blizzard and ice storm warnings are no longer sent to phones by the National Weather Service, some local authorities continue to send winter weather related alerts at their discretion; for example in New York City during the January 2015 North American blizzard, alerts were sent to people's cell phones to warn users of a travel ban on New York City streets.[16]

Notable uses[edit]

  • Boston Marathon bombing — A shelter-in-place warning was issued via CMAS by the Massachusetts Emergency Management Agency.[17]
  • A child abduction alert in the New York City region in July 2013 for a 7-month-old boy who had been abducted. The massive inconvenience caused by the 4:00 am timing raised concerns that many cellphone users would choose to disable alerts.[18]
  • A blizzard warning in February 2013 for New York City.[19] (Note: As of November 2013, blizzard warnings are no longer included in the CMAS program.)[15]
  • A shelter-in-place warning for New York City in October 2012 due to Hurricane Sandy.[20]
  • A child abduction alert in the New York City Region on June 30, 2015, for a 3-year-old girl who had been abducted.[21]
  • 2016 New York and New Jersey bombings — A wanted alert was issued in New York City with a suspect's name two days after the bombings.[22]

See also[edit]


  1. ^ "Wireless Emergency Alerts (WEA)". FCC.gov. Retrieved 2015-07-15. 
  2. ^ a b "Emergency alerts coming to your cellphone via SMS - GadgeTell | TechnologyTell". GadgeTell. 2008-04-14. Retrieved 2015-07-15. 
  3. ^ a b c d e "Wireless Emergency Alerts (WEA) | FCC.gov". Beta.fcc.gov. Retrieved 2015-07-15. 
  4. ^ "Cell Broadcast ; One2many" (PDF). Eena.org. Retrieved 2015-07-15. 
  5. ^ "Common audio attention signal.". CFR Title 47, Part 10, §10.520. U.S. Government Printing Office. Retrieved 3 April 2014. 
  6. ^ a b [1] Archived December 13, 2009, at the Wayback Machine.
  7. ^ a b "Wireless Emergency Alerts (WEA) : Background". Fcc.gov. Retrieved 2015-07-15. 
  8. ^ "Wireless Emergency Alerts". Ctia.org. Retrieved 2015-07-15. 
  9. ^ [2] Archived June 13, 2011, at the Wayback Machine.
  10. ^ "Amber Alerts, other urgent warnings to be extended to cellphones by next April". The Globe and Mail. Retrieved 7 April 2017. 
  11. ^ "Telecom Regulatory Policy CRTC 2017-91". CRTC. Retrieved 7 April 2017. 
  12. ^ "National Emergency Alert System Goes Live". Government Technology magazine. 10 April 2012. 
  13. ^ "Wireless Emergency Alerts: Frequently Asked Questions". Nws.noaa.gov. 2014-05-16. Retrieved 2015-07-15. 
  14. ^ Karnowski, Steve (2012-06-28). "Weather Alerts Coming Soon to Smartphone near You". Associated Press. Retrieved 2012-06-30. 
  15. ^ a b "Service Change Notice 13-71 - National Weather Service Headquarters Washington DC". National Weather Service. November 13, 2013. Retrieved February 14, 2015. 
  16. ^ "Why NYC smartphones got blizzard alerts, but no one else did". Mashable. Retrieved February 24, 2015. 
  17. ^ "How Can Wireless Emergency Alerts Benefit Local Media? Boston Bombing Shows How | Emergency Alert System | Galain Solutions, Inc". New.galainsolutions.com. 2014-06-20. Retrieved 2015-07-15. 
  18. ^ "Early Morning Alert Issued After 7 Month Old Boy Is Abducted". The New York Times. Retrieved 2015-07-15. 
  19. ^ "Blizzard Wireless Emergency Alerts: Why Only Some People Got Them - ABC News". Abcnews.go.com. 2013-02-07. Retrieved 2015-07-15. 
  20. ^ "Hurricane Sandy Wireless Emergency Alerts: Why Only Some People Got Them - ABC News". Abcnews.go.com. 2012-11-01. Retrieved 2015-07-15. 
  21. ^ "Amber Alert canceled for 3-year-old girl abducted in East Harlem | New York's PIX11 / WPIX-TV". Pix11.com. 2015-06-30. Retrieved 2015-07-15. 
  22. ^ Robertson, Adi (2016-09-19). "Wireless alerts sound for NYC bombing suspect". The Verge. Retrieved 2016-09-19. 

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