The porn industry has become an eager early adopter of new technology on Apple's latest mobile phone.

Using the the iPhone 4's videoconference feature, companies have developed video-sex chat services and are hiring workers through internet adverts in the US.

With more than three million of the phones already sold, the adult industry stands to make big money.

In at least five cities internet adverts seek models specifically for video sex chat on the phone's FaceTime feature. Many even offer to throw in a free iPhone 4 for the new employees.

FaceTime lets people call another iPhone 4 user and have live video conversations over a Wi-Fi connection through the phone's camera and screen. In one TV advert, a soldier uses it to get a look at his faraway wife's ultrasound pictures.

The adult industry wants its customers to share moments of an entirely different kind with its stars. And while the technology may be new, the idea is not.

In the 1970s, the demand for explicit videos at home helped VCRs become widespread, and the industry was the first to embrace DVDs, too. internet porn peddlers were some of the first to make wide use of streaming video and online credit card payments.

"The first time someone created a camera there was someone who said, 'Wouldn't it be good for someone to take off their clothes in front of this camera?"' said Michael Gartenberg, vice president at Interpret, a media research company.

And for years, cameras mounted on computers have helped connect people for racy online video sessions. But the portability and privacy of a mobile phone makes FaceTime a new frontier for the industry.

"A phone is such an intimate thing, you usually don't lend it out or have someone else use it," said Quentin Boyer, of Pink Visual, an adult production company.

He said his company began planning for iPhone 4 video services almost as soon as the device came out. They should be ready in a matter of weeks.

He said the company will offer FaceTime sessions with some of the same women who appear in its videos.

"It has a very personal feel - your mobile phone to hers," he said.

The rise of FaceTime porn puts Apple in an awkward position. Its competitors have products that allow video chat, too - HTC's Evo 4G phone, for one. But Apple has made a point of keeping applications sold in its iTunes store clean.

Apple has rejected book apps for featuring sexual content and political satires for their potential to offend. While some rejected apps have been approved after revisions, Apple has kept one strict rule: No porn.

FaceTime is not even an outside developer's app, but a main feature of the phone.

Watchdogs worry that FaceTime could connect children to pornography or predators. Parents can put computers in public areas of the home to supervise internet usage, but mobile phones go anywhere.

"Unfortunately, both children and sexual predators are often ahead of parents when comes to technology," says Donna Rice Hughes, president of Enough Is Enough, a child safety group.

Apple said that people can choose whom they chat with and parents can turn off the FaceTime feature.

Another obstacle is that the iPhone 4 camera was designed specifically for face-to-face chatting.

"You can have the phone on your face, or other body parts, but not both at the same time," said Teagan Presley, who acts in adult films and performs in video chats. "Most customers want the full package, and it's going to be difficult holding a phone."