The Federal Emergency Management Agency announced a text message-based emergency alert system for enabled mobile devices.

The Personal Localized Alerting Network, or PLAN, will allow customers who own an enabled mobile device to receive geographically-targeted, text-like messages alerting them of imminent threats to safety in their area, such as a tornado.

PLAN enables government officials to target emergency alerts to specific geographic areas through cell towers, which pushes the information to dedicated receives in PLAN-enabled mobile devices. Cellphone service congestion should not be a problem. Only three types of alerts will be issued through the system: alerts from the President, alerts involving threats to life and safety and Amber Alerts.

Not all mobile devices are equipped to receive the alerts. Currently, some versions of the iPhone and Android have the required circuitry, but will require a software update.

PLAN complements the existing Emergency Alert System, which uses mass media outlets to warn the public of imminent danger. Wireless companies will volunteer to participate in the program, and must activate the technology by April 2012. AT&T, Sprint, T-Mobile and Verizon will offer PLAN alerts ahead of that schedule. The service is free and customers of participating networks are automatically signed up.

The announcement of PLAN comes not long after dozens of tornadoes wreaked havoc throughout the South. Some truckers in the effected area were unaware of the storms and caught off-guard. The new system will potentially help warn drivers in future events.