MIAMI, Florida (Reuters) -- Cell-phone pornography is a fast-growing business that analysts expect will generate about $2 billion in global revenue by 2009.

And porn-on-the-go was the focus of a two-day Mobile Adult Content Congress that wrapped up in Miami on Thursday amid expectations, according to at least some participants, that it will soon catch on in the United States.

Consumers already spend tens of millions of dollars a year on cell-phone-based adult content in Europe where companies such as mobile-phone giant Vodafone Group Plc -- or "Vodafilth" as it was dubbed by one British newspaper -- are among the distributors.

Leading American cellular carriers have been reluctant to jump onto the bandwagon, however, fearing a backlash from the conservatives and the religious right if they provide U.S. consumers easy access to hand-held X-rated theater.

The Miami conference, aimed at allaying some of those concerns, was sponsored by Waat Media, a California-based company that represents some of the leading so-called late-night U.S. entertainment brands.

Rather than focusing on steamy content or images, such as video footage featuring conference attendee Ron Jeremy -- a porn star who has licensed his name to RJ Mobile -- industry officials focused here on issues such as content rating and filtering devices or age verification mechanisms, meant to prevent underage consumers from buying adult content.

It was all a bit staid and very business-like, but one speaker, an executive identified as James Walz of West Management, did seem to get worked up as he talked about features like "personalized strip teases" and unbridled U.S. market potential.

"There's a huge consumer demand following up on the immense success of the Internet," Walz said. "It's a sizzling, serious business."

U.S. sales of erotica or porn distributed via cell phones were estimated at no more than about $30 million last year.

But Adi McAbian, Waat Media's managing director, told Reuters that U.S. revenues could soon hit about $500 million per year, once the right technology, and services such as "robust age verification," are in place.

One key to future growth, apart from an avoidance of excessive regulatory controls, will be the ability U.S. consumers should have to get billed for adult content directly by their cell-phone providers, McAbian said.

"There's no doubt it's a huge market forthcoming. Long-range it's a huge market," he said.

On a global basis, Juniper Research, which specializes in research on the telecoms industry, says sales of adult mobile services are seen tripling between 2004 and 2009 to $2.1 billion.

Tina Southall, director of content standards at Vodafone, told Reuters adult offerings were a key part of the company's multimedia strategy across Europe.

But what sells in Austria or Hungary, which she described as Europe's "most explicit markets," or even in Ireland, Britain and Sweden, which she ranked as Europe's "most conservative" venues, may not play in Peoria, Illinois.

Jeffrey Nelson of Verizon Wireless, the U.S. cell-phone service that Verizon Communications Inc. shares with Vodafone, said the company had absolutely no plans to offer adult content on its mobile phones.

"As my grandmother would have said, 'fat chance,'" Nelson said.

"I hear all the same things you do about analysts saying this is a big boom," he said. "We don't think that our customer base wants it."