It was almost 11 p.m., and Jay Cuccia stood in the nearly empty parking lot of the Marley Station mall in Glen Burnie, waving a walkie-talkie in the air.

Police officers and firefighters depend on the brick-size device for emergency communications, but at this spot in the shadow of two nearby cell phone towers, its signal was overwhelmed. A woman's voice hiccupped and buzzed with static. Cuccia made a quarter turn. No better. He stepped back a few paces and gripped the antenna. A marginal improvement. Half a dozen engineers from three cell-phone companies watched as Cuccia, Anne Arundel County's communications officer, tinkered.

About once a month, Cuccia and his team assemble late at night for a "can-you-hear-me-now?" session to troubleshoot walkie-talkie problems. They are on the front lines of the national conflict between public safety communications systems and ever-increasing mobile phone traffic. The stubborn problems in the mall parking lot show that solutions won't come easily.

Some of the interference occurs when cell-phone signals combine and overpower the weaker signals of public safety radios. But most of the problems stem from the phone traffic of Reston-based Nextel Communications Inc., which uses frequencies sandwiched in slivers between those used by public safety agencies.

Nextel and its competitors are feuding over rival proposals before the Federal Communications Commission to rearrange frequencies to separate Nextel from the emergency communications systems. With billions of dollars in costs and airwave rights at stake, platoons of lawyers and lobbyists are working the issue in Washington.

Anne Arundel County already has moved ahead with part of Nextel's broader plan. Engineers from the county, Nextel and its rival carriers last year devised their own solution: The county arranged a deal to swap frequencies with Nextel for less-congested ones, and everyone involved pledged to fix any remaining problems.

"We've basically become a test laboratory for this problem," Cuccia said. Since it switched to its new frequencies in January, the number of problem spots have decreased more than 90 percent, he said. "It's working, but at significant taxpayer expense."

Even after a $35 million upgrade of its emergency communications system, the county has spent more than $200,000 fixing remaining problems, which eat up a third of Cuccia's time.

Police and fire officers in Anne Arundel County first noticed communication dead spots in late 1998. Cuccia's department started getting calls complaining that signals from the radios would fade or stop.

"They started learning where the problems were," Cuccia said. Police in patrol cars would pull over errant drivers only where they knew they could get a signal to dispatchers if they needed backup.

In early 1999, a serious car accident near Marley Station served as a wake-up call. Emergency workers sent to the scene couldn't communicate with the 911 dispatch center.

"It's the explosion of the cellular technology," said Jeffrey Martin, the county's technical consultant. "Everyone has to have a cell phone," he said, so the cellular companies kept building towers to carry more traffic.

In 2000, the county began upgrading its emergency communications system. The county plotted the 170 cell-phone towers in the county on a map and developed software to predict where emergency radios might be overpowered. Cuccia and Martin drove around in the county's beat-up Ford Club Wagon testing along the roads.

Much of the testing is done at night, when relatively few people are making cell-phone calls, so cell-phone company engineers can unplug some of their towers, then bring them up again slowly to figure out which carrier's signal is causing interference.

Sometimes the police pull Cuccia over because the van he now uses, bristling with antennas, looks suspicious cruising slowly through a neighborhood at night.

Of 61 trouble spots originally identified by the county, at least 50 were caused by Nextel's signal, said Liang Li, the engineer from Nextel who usually accompanied Cuccia and engineers from Cingular Wireless and Verizon Wireless on the fix-it outings.

"We recognized that we had to do much more to mitigate interference," Li said. In some cases, Nextel reduced its power to one-fifteenth normal levels, risking dropped calls on its own network to preserve the public safety signal, he said.

Disentangling Anne Arundel County's frequencies from those close to Nextel has reduced the problem to a half-dozen bad sites. Marley Station remains among them.

"It's still better," Martin said.

Now, the night meetings take place less often, as Cuccia and his team keep working on lingering problems and on new ones created by new cell towers.

During a recent meeting in a parking lot near the Capitol Raceway, just north of Crofton, Len Cascioli, a Nextel engineer, stared at his cell phone and waited for word that his carrier's signal had been turned off to test for interference.

"This is the life of a tester," he said with resignation after midnight. The engineers had been waiting for half an hour, turning on and off their signals to test the walkie-talkie.

Nearby, Bryan Dorbert, Verizon Wireless's engineer, ran back to his car and pulled out a portable spectrum analyzer to see which carrier's signal was still up.

"You guys are spoiled," Cascioli said of Dorbert's fancy equipment.

Meanwhile, Cuccia walked in circles listening to the sounds from his walkie-talkie. The culprits at that location, he said, appeared to be Nextel and Cingular. When their signals are at full power, the voice at the other end sounds like it's coming through a pillow, or it cuts out entirely.

Sometimes, Cuccia said, the routine wears thin. "I've spent many sleepless nights."

Jerry Minarick takes calls at the Anne Arundel County 911 center. Cell-phone traffic has interfered with some police and fire emergency communications.Liang Li, left, of Nextel Communications and Jay Cuccia, the Anne Arundel County communications officer, work in the field to determine the location and extent of cell-tower interference.Anne Arundel uses sophisticated equipment to detect communications problems.