Microsoft Corp. yesterday signalled serious interest in mobile when it announced the acceptance of ads on the U.S. version of its MSN Mobile portal. But its deal for content is worthy of note as well.

The software giant has entered into an exclusive deal with leading mobile entertainment content provider Thumbplay for MSN Mobile users. The deal also coincides with new MSN Mobile features that include astrology and movie tickets.

"I think what's special about this is that we're being integrated into Microsoft's WAP properties in a contextual manner," said Chris Phenner, senior vice president of business development at Thumbplay, New York.

The MSN Mobile portal receives more than 120 million unique monthly visitors in the United States, per comScore Media Metrix data for October.

Mobile content from Thumbplay will be integrated within the MSN Mobile Web and WAP sites.

Through Thumbplay's contextual integration on these sites, visitors can buy and download relevant ringtones, wallpapers, games and video clips to more than 2,000 supported handsets, including 16 Windows Mobile-based devices. Ringtones will be offered first.

A link on MSN Mobile will take users to a co-branded Thumbplay page. Fifty thousand ringtones are offered here, with links that take users back to the MSN Mobile homepage.

Content is available for purchase on a one-off or monthly membership basis. MSN Mobile gets a cut on every ringtone sold. The charges appear directly as an SMS message and seen on the consumer's wireless bill.

Thumbplay technology allows Alltel, AT&T Wireless, Sprint, T-Mobile and Verizon Wireless subscribers to buy content across their wireless networks.

These wireless carriers host portals such as MSN Mobile.

The MSN Mobile deal was made public three months after Thumbplay inked a similar arrangement in September with Time Warner Inc.'s AOL LLC. Thumbplay is contextually integrated on AOL Music's Web site and also the WAP site at wap.aol.com.

Thumbplay's deals with large interactive media companies such as Microsoft and AOL for exclusive content point to the opportunities as well as the challenges in the mobile field.

"We find that whether you're talking about Web-based or WAP-based delivery of mobile content that this is far from straightforward," Mr. Phenner said.

"Billing relationships with carriers, handset support to more than 2,000 devices and 24-hour customer support are not service features commonly found," he said.