CBS left no stone unturned in its pursuit of mobile advertising dollars last week, inking deals with four mobile ad firms.

The network partnered with mobile ad networks Third Screen Media, AdMob, Millennial Media and Rhythm NewMedia to build mobile ad offerings for CBS’ news and entertainment content on cell phones, including text and banner ads, mobile Web site ads and video ads.

"We believe mobile advertising is one of the biggest business opportunities in the mobile world, and we want to be at the forefront of it," said Cyriac Roeding, executive VP for CBS Mobile, in a statement. The new deals will let CBS reach big-brand advertisers as well as niche advertisers, he added.

Advertising in mobile content is a small but growing market. The market for mobile advertising in the United States last year reached $421 million and is expected to grow to $4.8 billion in 2011, according to market research firm eMarketer.

Partnering with a mobile ad network is the fastest way to experiment in the mobile ad business, said John du Pre Gauntt, analyst with eMarketer. "Right now people’s habits are still kind of fluid. You want to be out there first to lock in that habit."

Consumer adoption rates for mobile video are increasing quickly. About 4 percent of the mobile phone-using population in the United States, or 8.4 million people, subscribe to mobile video, up from less than 2 percent in the year-ago period, according to mobile research firm Telephia. Revenue for mobile video tripled in the first quarter of 2007 to $146 million.

That’s why smart networks need to jump out in front with content and monetization strategies, Mr. du Pre Gauntt said.

Mobile video is an attractive ad venue because viewers watching mobile video usually are highly engaged, especially in comparison to TV watchers, he said.

Most of the dollars for mobile content have gone to text and banner ads on mobile Web sites, but advertisers and networks have begun to explore ads in mobile TV.

Earlier this year, MTV Networks struck a deal with Intel and Pepsi to sponsor mobile TV. In June, Third Screen Media, an AOL-owned company, linked up with Discovery, which is using the software to serve ads for Discovery Channel and Discovery Health Channel. Discovery also will use the software for an additional 12 to 14 mobile ad campaigns this year.

Also, Yahoo! partnered in March with mobile TV service provider MobiTV to serve as the ad network for MobiTV’s mobile video ad sales.
CBS will use AdMob to serve ads on mobile Web sites, Millennial Media to provide text and banner ads on Web sites and video, Rhythm NewMedia to deliver targeted video ads and Third Screen to sell ads for CBS mobile sites.