Twenty-three percent (58 million) of all U.S. mobile subscribers say they have been exposed to advertising on their phones in the past 30 days, according to a new report out today from The Nielsen Company. Half (51% or 28 million) of all data users who recall seeing mobile advertising in the previous 30 days say they responded to a mobile ad in some way.

The findings come from the bi-annual Mobile Advertising Report from Nielsen Mobile, a service of The Nielsen Company, and are based on a survey of more than 22,000 active mobile data users who used at least one non-voice mobile service in the fourth quarter. In the report, Nielsen examines consumer recall, responses and attitudes toward banner ads on mobile web pages, SMS text-message advertising, sponsored applications, video advertising and other types of advertising that reach consumers while using data applications on their mobile phones.

The study further reveals that

• The number of data users who recalled seeing mobile advertising between the second and fourth quarters of 2007 increased 38% (from 42 to 58 million subscribers)
• Teen data users (ages 13-17) were the most likely age segment to recall seeing mobile advertising (46% recalled seeing some type of mobile advertisement, compared to 29% of all data users) 
• Asian-Americans and African-Americans are more likely to recall mobile advertising (42% and 40%, respectively) than all data users
• 26% of those who saw an ad responded at least once by sending an SMS text-message, the most popular ad response. 9% say they have used click-to-call to respond to a mobile ad, where users follow a link on their phone to call a specific number
• 32% of data users said they are open to mobile advertising if it lowers their overall bill
• 13% (18% of males) said they are open to mobile advertising if it improves the media and content currently available 
• 14% said they are already open to mobile advertising so long as it is relevant to their interests
• 23% expect to see more mobile advertising in the future (up from just 15% in Q1 2007)

While media companies and marketers explore the unique ways they can interact with consumers over the highly personal mobile platform, supporting mobile media content through advertising revenues, advertising researchers must examine the ways in which audiences are and are not willing to engage with mobile advertising.

"We see an increasing trend of consumers willing to trade off and receive advertising to gain more -- and better -- mobile content," said Jeff Herrmann, VP of Mobile Media at Nielsen Mobile. "Successful mobile marketers will meet the challenge offered by consumers by engaging with them in a way that adds value to the mobile user content experience."