Washington ? A new report by a public safety group throws into question the ability of police and firefighters to locate people through their cell phones when they dial 911 in an emergency.

The study is believed to be the first independent evaluation of wireless location technology and sends a clear message: Do not assume rescuers will know where you are if you call 911 from a cell phone.

The report was commissioned by the Association of Public Safety Communications Officials International (APCO), a group that has long been concerned about the limitations of the technology and the public’s unrealistic expectations of what it can deliver.

The Associated Press was given an advance copy of the study, which will be officially released in May.

Carriers are required to test their location systems and to be able to pinpoint callers within certain distances. But they are not required to share their test results with 911 dispatchers, police and firefighters. And the Federal Communications Commission does no testing of its own.

So using a grant from the Public Safety Foundation of America, APCO began work in August of 2005 on Project LOCATE, to find out on its own how well the systems were working.

The answer? Not very well.

“We were hopeful that the information that they were seeing on a wireless call would be closer to the location than it was,” said project chairwoman Nancy Pollock. “We were very disappointed.”

Tests were conducted in seven different communities across the country – Palo Alto, Calif.; Marion County, Fla.; Jasper County, Mo.; Onondaga County, N.Y.; Rowan County, N.C.; Bexar County, Texas; and Laramie, Wyo. The cities were selected based on topography, demographics, existing technology and other factors.

APCO declined to identify the cell phone companies in its report and was careful in its criticism of the industry. But the details tell the story.

The FCC requires companies that use “network” technology – triangulating among cell towers to determine the caller’s location – to come within 300 meters of the caller 95 percent of the time.

The company identified as “carrier No. 001” in the testing was unable to come within 300 meters of the 911 caller 73 percent of the time in Onondaga County; 64 percent of the time in Marion County; and 61 percent of the time in Jasper County.

Two companies tested used network technology primarily while five used “handset” technology, meaning they use global positioning system satellites to locate callers. Federal rules require companies using satellites to come within 150 meters for 95 percent of calls.

Results varied based on carriers and geography. A few communities, however, stood out for poor performance, among them Marion County, Fla.; Onondaga County in New York and Jasper County, Mo.