America's second-largest wireless carrier AT&T on Friday announced it will be pushing out an update to subscribers who own an iPhone 5 or 4S, with the new software supporting an FCC-mandated Wireless Emergency Alert system.

Update: Readers are reporting the iPhone 4 is also receiving the OTA update in some areas.

AT&T said it will begin rolling out the software update for Wireless Emergency Alerts (WEA) today, which will allow iPhone 5 and iPhone 4S owners to receive government-issued safety messages in the form of text-like messages.

The U.S. Federal Communications Commission, non-profit trade organization for the wireless industry CTIA, and the Federal Emergency Management Agency have cooperated to create the WEA system. As noted on the CTIA's website, WEA-capable mobile devices began receiving alerts in April 2012.

There are three types of alerts:

Presidential Alerts â Alerts issued by the President or a designee;

Imminent Threat Alerts â Alerts that include severe man-made or natural disasters, such as hurricanes, earthquakes, tornadoes, etc., where an imminent threat to life or property exists; and

AMBER Alertsâ Alerts that meet the U.S. Department of Justice's criteria to help law enforcement search for and locate an abducted child.

While the alerts will come to users in something resembling a text message, the system actually uses a different, faster technology. Subscribers won't be charged for incoming alerts.