Mobile operators will have to look at retooling their business model to one funded by advertisements rather than subscriptions as revenues come under greater pressure, an industry research firm said on Tuesday.

"In the future, a mobile business model could look much more like broadband and Internet economics, with the operator charging for access to the Internet and deriving advertising and click-based revenues," said Mark Newman, chief research officer at Informa Telecoms & Media.

Mobile operators have already begun embracing that trend, Informa said, citing recent moves by Vodafone Group and Hutchison Whampoa's 3 to offer cheaper services for customers who accept advertisements on their mobile phones.

Vodafone, the world's biggest mobile operator outside China, last week announced a deal with Yahoo Inc. that will allow customers who agree to accept targeted display advertisements to get savings on certain Vodafone services.

Hutchison's 3 Group has unveiled a raft of partnerships with companies such as Yahoo, Google and Skype as part of a move to position itself more as a mobile media company rather than a mobile operator.

Informa expects worldwide spending on advertising targeted at mobile phones to grow to $11.35 billion by 2011 from $871 million this year as cell phones become the next frontier for advertisers.

The London-based research firm said the mobile industry was predicting a bullish outlook for next year but that the sense of optimism was greater among handset makers and equipment vendors than mobile operators.

A survey of more than 1,800 senior industry professionals carried out by Informa showed that 65 percent of respondents felt more confident about the mobile industry's prospects.

Among operators, many of whom are seeing slowing revenue growth alongside threats from increased regulation and changing technologies, the figure was only 54 percent, Informa said.