The National Association of Broadcasters (NAB) and CTIA continue to clash over the FCC's plan to sell off more television airwaves to the wireless industry.

The escalating war of words between the two groups was sparked by a speech from FCC Chairman Julius Genachowski at the Mobile Future Forum in Washington, D.C.

In the speech, Genachowski touted the agency's proposed incentive auctions of television broadcast spectrum and characterized the auctions as a win-win for broadcasters, the wireless industry and the federal budget. The auctions would free up about 120 MHz for the wireless industry and bring in an estimated $33 billion to the treasury.

Genachowski also said that the FCC had completed a "baseline" spectrum inventory which provided additional evidence supporting the need for the incentive auctions.

The NAB has issued multiple statements arguing with Genachowski's plan, prompting the leaders of CTIA and the Consumer Electronics Association (CEA) to pen their first-ever joint letter to lawmakers protesting the NAB's claims.

"CTIA and CEA suggest that the broadcast industry focus on the overwhelming evidence presented by the Federal government and the wireless and consumer electronics industries of the staggering growth in demand for mobile broadband services," CTIA President and CEO Steve Largent and CEA President and CEO Gary Shapiro wrote. "For NAB to ignore the evidence and continue stalling on voluntary reallocation of broadcast spectrum will deny U.S. consumers the technologies and services they need as well as the billions of dollars that will flow to the U.S. Treasury."

The NAB, hesitant to give up more television airwaves after the 2008 auction, has been wary of the plan and wants the FCC to conduct an inventory of the country's spectrum assets before moving ahead with the auctions. CTIA is pushing the FCC to conduct the auctions before doing a spectrum inventory.

In a statement, NAB President and CEO Gordon Smith claimed that broadcasters' used spectrum more efficiently than wireless operators and repeated the group's request for a spectrum inventory.

"We would respectfully ask for an independent study to confirm Chairman Genachowski's assurances that spectrum suitable for wireless broadband is not lying fallow, given recent verbatim remarks to the contrary from current FCC licensees," Smith said, alluding to comments from Dish Network and Time Warner Cable executives that suggested the companies were holding onto their bandwidth for financial gain, versus using it for wireless services.

He later challenged the validity of the FCC's spectrum inventory.  "The question is not whether the FCC can identify locations and licenses on the spectrum dashboard that have been set aside for specific services. The real issue is whether specific companies that bought or were given spectrum worth billions have actually deployed it," he said.

NAB's alleged spectrum hoarding has been a major source of disagreement between the two groups, which have repeatedly clashed over the issue. CTIA doesn't want the proposed broadcast auctions to get derailed by the NAB's spectrum hoarding allegations and says bandwidth warehousing isn't the source of the looming spectrum shortage.

Largent quickly responded to Smith's statement, saying in a written response that broadcasters were "simply wrong" to suggest that U.S. wireless companies are hoarding spectrum and repeated his call for the FCC to move ahead with its planned broadcast auctions.

"NAB has once again endeavored to search for any hint of outlier instances where spectrum allegedly is not being put to productive use – a point that has been consistently refuted by the facts," Largent said. "At times, they have called for either an independent review of spectrum demand, or that an inventory is pursued before moving forward with a reallocation of any broadcast spectrum.  These are odd requests coming from an organization that purports to support voluntary incentive auctions."

Some broadcasters with unused spectrum assets have been in favor of the FCC's proposal to let them sell off airwaves on a voluntary basis, but others in the television industry have been apprehensive of the plan.

Broadcasters handed over 108 MHz to the wireless industry during the transition from analog to digital television and some are opposed to relinquishing more of their airwaves to mobile operators.

CTIA and Genachowski say the auctions are needed to provide bandwidth to support rising demand for mobile data services. The FCC estimates the wireless industry will run into a spectrum deficit as soon as 2013.