Does the GPS on your cell phone work?

GRAND RAPIDS, Mich. (WOOD) - It's big news when it works -- cell phone signals leading police to overturned boats, to lost and injured deer hunters, to fleeing thieves, even killers.

But the technology couldn't pinpoint 3-year-old Ethan, who recently called 911 from a cell phone at his home near Sparta.

"Mommy's not waking up," Ethan told a Kent County dispatcher.

The call launched a desperate search by dispatchers and police for Ethan and his mom. "Do you know your colors yet?" the dispatcher asked.

"Yeah."

"What color is your house?"

No matter how hard dispatchers tried, they couldn't get a location through the cell phone.

"We're trying to find you, honey. We're trying to make sure we get to your house."

Finally, after a half-hour of detective work, rescuers tracked him down and revived his mom.

With more than three-quarters of 911 calls coming from cell phones, rescuers say their ability to track them is more important than ever. But just how close can they come to helping police find you?

Armed with a handful of cell phones, Target 8 put the system to the test.

Working with dispatch centers in West Michigan, Target 8 called 911 from as many as nine different cell phones at six different spots in Grand Rapids, Wyoming, southern and northern Kent County, and in Kalamazoo -- a total of 54 calls to 911.

Target 8 made eight 911 calls from inside Campau Parking Ramp, on Monroe Avenue NW, in downtown Grand Rapids. But dispatchers could not find us there, not once, no matter how fancy the phone -- though some were closer than others.

Instead, they thought the calls were coming from along the Grand River, in a nearby parking lot, across the Grand River, four blocks away on Ionia Avenue, back in the nearby parking lot, across the street from the ramp, back near the river, and, finally, 12 blocks away.

It was the AT&T iPhone that would have sent police scrambling a dozen blocks away to Grandville Avenue and Logan Street SW.

And, it was the $10 TracFone that came closest, just across the street from the ramp.

The phones were least accurate when Target 8 called from inside, including the partially open parking ramp.

They can be less effective when "calling from underneath a bridge, or a parking structure, or calling from a basesment of a house, calling from deep inside a department store," Kent County Dispatch Supervisor Matt Groesser said.

Or, from a corner table at Kelly's Restaurant in Cedar Springs.

"This one showed you, like, 14951 White Creek Avenue NE, which is a day-care center," a Kent County dispatcher said when answering a Target 8 test call from Kelly's.

That was the T-Mobile 4g Android MyTouch, and that day-care is more than a mile-and-a-half away.

Then, there was the At&T iPhone again -- this time off by more than four-and-a-half miles.

AT&T officials, when told about Target 8's results, asked for specifics, including the make and model of the phone, its operating system and when the call was made. After receiving that information, they refused to discuss the test results.

"I cannot provide any insight on the GPS testing," AT&T spokesman Jermaine Spight wrote in an email to Target 8. "We found no issues with our services during the time your test was conducted. AT&T fully complies with all applicable federal regulations regarding wireless E911 service."

T-Mobile officials also didn't respond to Target 8's request for a comment on the results.

When we called from outside the same restaurant, they came closer -- usually.

"As zoomed in as I can get," a dispatcher said during one of those outside calls. "It's like right at the front of the building."

Still, the AT&T iPhone showed us in a mobile home park just west of the restaurant.

In other tests, the phones came close -- outside Marge's Donut Den in Wyoming, at Woodland Mall, at 84th and US 131, though the At&T iPhone missed by 2 miles there, "finding" us in the 6500 block of Clay Avenue SW.

And, they were close in downtown Kalamazoo, though usually about a block or so away and never on the correct side of the road. Police say that is not close enough in the middle of a city and would force them to send a patrol car to the area, with windows rolled down, to search for the caller.

Dispatchers say accuracy depends on technology. Some phones use triangulation -- signals bouncing off 3 towers to pinpoint them. They can actually work better from inside than the phones with built-in GPS.

"Each technology has its own limitations," Groesser said.

Phones with built-in GPS work better outside than in -- as long as they have a clear line to a satellite.

"The bottom line is, know where you are," Groesser said.

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It was impossible to rank the cell phones tested by Target 8 because there are too many variables, such as tower locations, or whether we called from inside or outside. For example, the TracFone performed best in downtown Grand Rapids, but not as well in the city of Wyoming. The bottom line, dispatchers say, is to not trust the technology to