A company behind a subscription video service for mobile phones has launched an ad-supported, 24-hour free music video channel for Internet-enabled phones, computers and other portable devices capable of playing video.

The service, launched Monday by SmartVideo Technologies Inc., offers full-length music videos from recording artists such as U2, Kanye West and Mariah Carey, said Richard Bennett, president and chief executive of the Duluth, Ga.-based company.

SmartVideo has licensed thousands of videos, although not all of the major record labels have come aboard, Bennett said. He declined to name the record labels.

The company plans to add music video channels tailored to urban, dance, rock and other genres.

Users of the service, which is available throughout North America, must download copy-protection and licensing software to their portable device to see the music videos. At launch it was compatible with more than 100 handsets, but works with any wireless carrier, Bennett said.

As wireless technologies have improved, the amount of content for mobile phones and other portable devices has surged. Last fall, Apple Computer Inc. began selling music videos and TV shows such as "Lost" for viewing on its iPod for $1.99.

An Apple spokesman declined to comment late Tuesday on how the SmartVideo service might affect sales of music videos on iTunes. Earlier this month, Apple said it had sold 8 million videos — both music videos and TV shows — on iTunes.

Major wireless carriers have also been increasingly offering streaming television shows, news and music videos. The concept of ad-supported, full-length music videos is not new for Web sites such as Yahoo.

Still, Bennett hopes music fans won't balk at having to wait through the 10- to 15-second ads between every second or third video as long as they can get the content for free. Mobile phone users will still have to pay whatever their carrier charges for streaming content off the Internet.

"We're going to experiment with different ad formats ... [to] find out what they'll tolerate," Bennett said.