The report is the first in a series of quarterly updates on mobile advertising to be issued by mobile entertainment company Limbo in partnership with Britain-based market research firm GfK NOP Research.

Among other key findings, the report confirmed that SMS text messaging remains the dominant non-voice service used by U.S. mobile subscribers, with 56% tapping away on phones. Mobile gaming and surfing the mobile Web were both about half that percentage, while less than 10% watch mobile TV.

Of the one-third of cell customers who have seen mobile ads, most received them via SMS or MMS text messaging. "A third of mobile phone owners saying they've seen advertising on their phones is significant," said Rob Lawson, CMO at Limbo, which creates games and other mobile content. "It means the first hurdle has been crossed to reaching the mass market."

But he acknowledged that marketers are still trying to figure out the best way to reach consumers on mobile phones, where media and ad formats are still evolving. "Brands are just waking up to the medium, looking at what works and what doesn't work. Hopefully, we can provide some data that helps to solve that conundrum," Lawson said.

The study found those who recalled seeing mobile advertising, one-third remembered brands being promoted. Among the brands with the highest recall were familiar names such as Verizon, Motorola, MTV, Coke, McDonald's and Chevrolet.

In terms of demographic data, men were found to have 20% higher advertising recall than women. Meanwhile, African-Americans had twice the recall of whites and those under 24 had twice the recall of those over 50.

When it comes to SMS texting, 82% of active users were under 24 and African-American and Hispanic consumers were 50% more likely to be SMS users than white ones. Single people were half again as likely to text as married people.

The study conducted by GfK NOP on behalf of Limbo was based on a survey of 1,000 adult U.S. mobile subscribers interviewed by phone.

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