Public-safety officials and consultants largely blame cost disputes with Sprint Nextel, which is bankrolling the $2.8 billion project. They fear the spectrum transfer, which began in July and is to be completed by mid-2008, could be delayed or done improperly, further hindering communications.

Sprint Nextel says the disputes were to be expected.

"We have significant concerns that the process has been stalled," says Robert Gurss of the Association of Public-Safety Communications Officials, which last week voiced its concerns to the Federal Communications Commission. "Interference could endanger lives."

Since the mid-1990s, Nextel cellphones have disrupted public-safety radio systems in hundreds of cities, including Seattle, Miami and Denver. The reason: Frequencies used by public safety and Nextel are interlaced. The problem sometimes hampers emergency response, such as when firefighters at a 2004 Elks Lodge blaze in Mesquite, Texas, could not use their walkie-talkies.

That year, the FCC approved a plan to move Nextel and public safety to separate blocks of spectrum. Sprint Nextel, which acquired Nextel last year, will get prime airwaves valued at $4.8 billion. In exchange, it must give up airwaves worth $2 billion and pay for retuning radios, estimated to cost $2.8 billion. But if retuning costs more, Sprint Nextel must pay up, even if it loses money.

That caveat has prompted the company to dispute nearly all of the dozens of funding requests public-safety agencies have made and to not even respond to many of them, say emergency responders and their biggest adviser, RCC Consultants. Unresolved feuds are being reviewed by a mediator whose decision can be appealed to the FCC.

Sprint Nextel "is arguing over every cent," says RCC chief Mike Hunter. For instance, he says, the company disputed the $14,000 that Manasass, Va., schools seek to retune radios for their buses, saying $8,000 should be sufficient.

Sprint Nextel denies pinching pennies. "We are committed to spend whatever it takes" but want to "make sure costs are appropriate," says company executive Geoffrey Stearn.

Public-safety agencies and RCC also assail the project's managers, led by BearingPoint. Despite netting more than $20 million in fees so far, the managers haven't closely monitored negotiations or prodded Sprint Nextel to be more responsive, they say.

BearingPoint's Brett Haan, who's overseeing the swap, said the managers "take the concerns of public safety very seriously" and are working "to make sure the (project) is fast, fair and efficient."