Your mobile phone may be one of the last spots around that's relatively free of advertising -- but not for long.

Media and advertising companies have found a way of latching on to people's handsets by beaming ads to them via Bluetooth, the same technology used in some hands-free headsets.

Here's how it works: When you're standing less than 10 meters away from a Bluetooth interactive billboard, window display or concert hall booth, you'll be asked if you want to switch on your Bluetooth function and accept a file. That file could be a video, a song or an offer of rebate coupons.

As you are strolling down the Champs Elysees, for instance, don't be surprised if one day Lancome, using the technology, invites you to test its newest perfume in a nearby shop. You may also find yourself on the receiving end of ad clips from Coca-Cola or a Warner Bros. preview of its Happy Feet animated film.

A mobile phone is the one electronic device most people carry with them at all times, so it is too good of an opportunity for media companies and advertisers to miss, says Nick Jones, wireless technology analyst at Gartner research house.

But mobile phone operators aren't showing much enthusiasm for Bluetooth marketing since it's free for the consumer and often does not generate extra revenues for them.

Instead, mobile operators such as Orange favor a rival technology to Bluetooth called Code 2D - or QR (quick response codes).

These bar codes, already used in Japan, are read by camera phones and send the user directly to a Web page. Accessing a Web site requires a subscription to a wireless Internet connection for which users usually have to pay.

Bluetooth does not answer all our needs for mobile marketing, Jean-Noel Tronc, head of Orange Mobile in France, told Reuters in an interview. For us, Code 2D is much better.

Orange, which also operates in the UK, Poland and Spain, has asked manufacturers -- starting in early 2008 -- to supply it with camera phones with Code 2D capabilities.

BYPASSING OPERATORS

But advertisers don't necessarily need the support of operators. After all, consumers can use Bluetooth to download files regardless of which operator they have chosen, or even without one.

So don't be surprised if Bluetooth ads become commonplace down the road. After all, they allow for better targeted and more relevant advertising than mass media like television or radio.

Mobile marketing is a one-to-one relationship, while TV or radio marketing is one-to-many, says Gartner's Jones. Mobile phones take this personalized form of marketing a step further.

Something else to take into account with such marketing is whether it will simply annoy consumers.

Fabien Beckers, CEO of Paris-based mobile marketing firm Kameleon, rejects the idea that such ads are just spam, since consumers receive them only on an opt-in basis.

Still, most agree that for Bluetooth marketing to work, consumers need to get something out of it. The picture of an insurance company's logo probably won't attract much interest.

It (mobile marketing) has the potential to become a significant player in the marketing world as TV advertisers struggle to get people's eyeballs, says Jon Hudson, senior vice President of PC, automotive and consumer business units at CSR, But it has to be more than 'your next McDonalds is 200 meters on the left'.

Some local authorities believe Bluetooth proximity communication has a future in the public services arena as well.

This month Paris City Hall has started offering maps and updated what's-on guides beamed from 20 of the city's self-hire bike stations, which have been all the rage since they were installed in July.

We are trying to test the public's ability to use Bluetooth and their appetite for such 'take-away' information, says Jean-Philippe Clement, the Paris City Hall IT official who oversees the bike station Bluetooth project.

(Reporting by Astrid Wendlandt)

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