In the latest twist to phone sex, porn purveyors are exploring ways to sell or give away pictures, sounds and even movie clips that can be downloaded to wireless phones.

Last month, Playboy Enterprises Inc. announced it would begin delivering phone porn to wireless users in the United States by early 2005.

But Playboy is only the first of numerous companies looking to wireless as a new outlet for porn as mobile phones get more advanced and come with bigger screens and Internet capabilities.

''All the major players in this industry are looking at wireless as a big, new channel,'' said Adam Zawel, an analyst at technology research company Yankee Group Inc.

While the porn industry is still only flirting with cell phones and other wireless devices for now, Zawel estimates by 2008 it will be a $90 million industry in the United States and a $1 billion business worldwide.

Soon, you - or the guy sitting next to you in the restaurant - may be able to dial up dirty pictures as easily as calling home. And if today's cell phone rings aren't disturbing enough, imagine one that moans erotically with every call.

In other countries, the popularity of phone porn is already on the rise.

In Turkey, for instance, one popular adult site is visited more than 7 million times a week by subscribers to the Turkcell phone network, according to Yankee Group. In Italy, the site gets more than 3 million hits a week from Vodafone network customers.

Playboy already sells to major wireless markets such as Germany, the United Kingdom, Australia and Brazil.

''Given the extraordinary success we've had with our wireless offerings around the world, we felt the time was right to expand our wireless content to the millions of U.S. subscribers,'' Randy Nicolau, president of distribution for the Playboy Entertainment Group, said in announcing the U.S. service. Playboy has offered few details of its U.S. service plans.

In the United States, officials at most mobile phone companies say they don't - and won't - directly offer porn, mainly out of fear they'll offend the majority of their customers.

''We're not going to offer adult content,'' said Ritch Blasi, spokesman for Atlanta-based Cingular Wireless, the nation's biggest cell phone company. ''We don't think it's compatible with our brand.''

Recently, Cingular even quit offering downloadable pictures of fully clothed porn stars, a service that was first available through AT&T Wireless, which Cingular bought in October.

That said, there's nothing to keep U.S. consumers with the newest cell phones from going to any third-party porn site in the world to download video clips of hard-core sex acts or pictures of naked men and women to use as screen wallpaper.

And they do.

A Canadian cell phone porn site, for instance, gets more hits from U.S. cell phone users than more mainstream sites such as MSN, according to Yankee Group's Zawel.

In the United States, the phone porn business is still so small that it isn't on the radar screen of regulators or anti-porn groups yet.

At the Federal Communications Commission, spokeswoman Rosemary Kimball said the agency hasn't made any specific rules relating to cell phone porn, nor has it had any requests to do so from lawmakers or others.

Anti-porn groups such as Morality in Media Inc., meanwhile, are so focused on fighting Internet porn that they haven't paid much - if any - attention to nascent business of phone porn.

''We would certainly want to discourage the major cell phone players from distributing obscene material,'' said Pat McGrath, spokesman for New York-based Morality in Media. ''But I would say right now Internet pornography is the 800-pound gorilla.

''Of course cell phone distribution might be the infant gorilla that could grow up to be that big,'' McGrath added. ''So it certainly bears watching.''