AT&T this weekend started rolling out emergency alerts to customers using iPhone 5 and 4S. The alerts will come as a software update that includes Wireless Emergency Alerts. 

The messages are government-issued safety messages that include AMBER Alerts, emergency alerts – such as man-made or natural disasters, and Presidential alerts.

According to a post on the company's websites, the Wireless Emergency Alerts are part of the FCC’s Commerical Mobile Telephone Alerts (CMAS) program and are mandated by law. Users may turn off alerts (except for Presidential alerts) if they choose. 

Users will see a message that states “Carrier Settings Update:  new settings required for your device have been installed” when the software has been updated.  After that, the iPhone 5 or 4S will receive all Wireless Emergency Alerts by default. 

While the software update is mandatory, users are not charged for the data to deliver it and Wireless Emergency Alerts will never count against the user'smessaging plan. The update will be sent to users with iOS 6.1 or higher.

AT&T noted that customers on eligible hardware but not on iOS 6.1.x will not receive the carrier update over-the-air. When they next update their software via iTunes, the update will include the current carrier settings.