Wireless Emergency Alerts (WEA, formerly known as the Commercial Mobile Alert System (CMAS), and prior to that as the Personal Localized Alerting Network (PLAN)), is an alerting network in the United States designed to disseminate emergency alerts to mobile devices such as cell phones and pagers.
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Background
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. 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.
The government issues three types of alerts through this system:
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.
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),
Participation
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. 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. Although not mandatory, several wireless providers, including T-Mobile, AT&T, Sprint, and Verizon have announced their willingness to participate in the system. 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.
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. Customers who have the capability of receiving CMAS alerts (also known as PLAN and WEA) will be automatically signed up by their carrier. If they do not want to participate they may opt to block most CMAS messages; however, CMAS regulations prohibit participating carriers from configuring phones to allow users to opt out of messages issued by the President.
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.
National Weather Service
The Commercial Mobile Alert System (CMAS), interface to the Wireless Emergency Alerts (WEA) service, went live in April 2012. The NWS began delivering its Wireless Emergency Alerts on June 28, 2012.
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 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.