In anticipation of the Federal Communication Commission's planned release of new net-neutrality rules later this week, a group of two dozen Internet companies published a letter on Monday urging FCC chairman Julius Genachowski to support rules that guarantee neutral, non-discriminatory Internet access for businesses and consumers.

"An open Internet fuels a competitive and efficient marketplace, where consumers make the ultimate choices about which products succeed and which fail," the letter states. "This allows businesses of all sizes, from the smallest startup to larger corporations, to compete, yielding maximum economic growth and opportunity."

Among the signatories of the letter are both longtime net-neutrality supporters like Google and newcomers like Facebook and Twitter. The list also includes Amazon, eBay, EchoStar Corporation, Mozilla, Sony Electronics, and TiVo.

The letter comes after a lobbying broadside from AT&T that accused Google of operating a telephone service -- Google Voice -- while claiming that the service shouldn't be subject to the regulations that govern traditional phone companies.

Although AT&T's specific concern appears to be with rules governing the fees telephone networks pay each other to connect calls, its broader aim as new FCC rules get rolled out is to avoid being subject to regulations that competitors like Google don't face.

AT&T's worries about net-neutrality rules have been echoed by a group of 20 Congressional lawmakers who earlier this month prompted the FCC to investigate Google Voice.

Last week, a group of 72 House Democrats sent a letter to the FCC expressing concern that net neutrality rules would dampen broadband investment.

A group of 44 technology companies that make networking and communications equipment, including Cisco, Alcatel-Lucent, and Motorola, also sent the FCC a letter last week expressing similar sentiment.

FCC chairman Genachowski is expected to unveil the proposed new rules on Thursday. And then the lobbying will begin in earnest.

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