The Amber Alert (search) system used by police to let the public know when a child is missing is being expanded to cell phones.

The wireless industry announced Tuesday that subscribers can receive text messages on their phones when an alert is issued. The service is available in every state and is free to subscribers of most major cellular carriers.

About 200 to 250 Amber Alerts are issued each year. The Internet (search), radio and television stations broadcast the information, which also is flashed on highway signs on major roadways in the area where the child is believed missing.

Cell phone users who want such information so they can aid in searches can designate up to five zip codes and would receive alerts if a child is reported missing in any of them. Subscribers would also be notified of alerts issued for their state or metropolitan area.

"With more than 60 percent of Americans owning wireless devices and seldom going anywhere without them, this initiative will significantly increase the reach of the Amber Alert program," said Steve Largent, president of the Cellular Telecommunications and Internet Association (search).

Subscribers with phones capable of receiving text messages can register at www.wirelessamberalerts.org or through participating carriers' Web sites. A typical message would include details about the missing child and contact information for reporting a sighting.

Since the alert system began in 1997, more than 200 children have been recovered, according to the National Center for Missing and Exploited Children, which teamed with the wireless industry to expand to cell phones.

The system is named for 9-year-old Amber Hagerman of Arlington, Texas, who was killed after being kidnapped while riding her bicycle near her home in 1996.