Microsoft Corp told the U.S. Federal Communications Commission on Monday it was confident that vacant television airwaves can be used for wireless services without interfering with broadcast signals.

The unused U.S. television airwaves would be available for other services by early 2009, when broadcasters are due to switch from analog to digital signals.

In a document filed with the FCC, Microsoft disputed the agency's recent finding that prototype Internet devices caused static on existing broadcasts.

The company said its first prototype had a defective internal component but that a new model worked successfully in a demonstration for FCC technical experts last week.

We remain confident that the unused channels in the television spectrum band can successfully be used without harmful interference to incumbent licensees such as television and wireless microphone services, Microsoft said in a statement.

Microsoft, computer chipmaker Intel Corp and other companies have been pressing the FCC to make the vacant airwaves available for use without a license, while broadcasters have expressed concerns about potential interference with their signals.

The companies hope the unlicensed airwaves could be used for a variety of wireless services, including high-speed Internet access, particularly in rural areas where such offerings can be scarce.

In 2004, the FCC proposed creating two categories of users for the airwaves: one for low-power, personal, portable devices like Wi-Fi and a second group for fixed commercial operations.

The FCC also proposed requiring that the devices include technology to identify unused spectrum and avoid interference.

The FCC has said it would set final technical requirements for devices to use those airwaves without a license by October.