U.S. marketers are preparing to target cellphones with advertising related to the user's location and life.

"It's always been the next big thing around the corner the last 10 years, and now we really feel that it is," said Brian Levin, chief executive of Useful Networks Inc., which helps companies connect with cellphone users.

Marketers would like to let a cellphone user know that there's a special shop just around the corner, or that there's a car-rental outlet in the terminal as they land in a city they're visiting for a vacation.

The online research firm eMarketer reported an estimate Wednesday that Japan's mobile ad market grew by more than 40 per cent in 2007. And eMarketer has predicted that U.S. mobile ads, worth less than $900 million in 2007, will top $4.3 billion in 2011.

The company said that in 2008, "mobile marketing will execute its first million-dollar-plus campaign and local mobile search will become a huge battleground among web giants, mobile operators and local directory publishers."

In the U.S., however, the marketers are facing some resistance from cellphone providers, who fear that providing detailed information about subscribers could cause the subscribers to leave.

"One thing I can guarantee Verizon Wireless will not do is get a bump of short-term advertising dollars while scaring and losing our customers in the process," spokesman Jeffrey Nelson said. 

On the other hand, the providers are aware that there's money in providing access, and some have found ways to do so without compromising the customers' privacy. Sprint phones allow advertisers to target groups by age or area, but Sprint Nextel Corp. receives the ad from the advertiser and sends it out.

That way, no data is shared, spokeswoman Emmy Anderson said.

Cellphone data, such as regions and numbers called, is key for marketers, because it can provide insights into the consumer's behaviour.

But under U.S. privacy rules, user permission is required to use and share cellphone records for marketing.

That has prompted U.S. industry trade groups, such as the Mobile Marketing Association, to set up committees to look into the issues and potential of cellphone marketing.

Even so, advertisers will have to be very careful, said Jarvis Coffin of Burst Media, which helps web companies attract advertisers.

"Are consumers going to be spooked by the idea that suddenly their phone goes beep and it's a Starbucks offer, and they are standing next to a Starbucks?"

With files from the Associated Press