Watch out for a bluejacker watching you

It was just another ordinary day at Waterloo station. The crowds milled around in front of the departure boards as a young teenage girl and her father approached.

They stopped and the girl got out her mobile phone. Grinning, she tapped a message into the phone and then looked around. She later described how "as soon as I sent the contact, I automatically went into alert status; ears pricked, listening out for that ghastly Nokia message received tone".

Less than 10 seconds later a woman wearing a pink, striped top stared at her phone in disbelief.

"Sure enough, it was her phone. Pink-stripy lady had just become my first memorable victim," wrote the girl. With a reluctant Dad in tow, she had him snap a clandestine camera phone picture of his daughter and her "victim".

The lady in the pink top had just been "bluejacked". It was this thrilling experience for a teenager which inspired Ellie, a 13-year-old girl from Guildford, Surrey to launch BluejackQ.com earlier this month. "Bluejacking" or "bjing" is the sport of "hijacking" people's mobile phones via their bluetooth wireless connection within a 10 metre range. Ellie now makes bluejacking a daily pastime and details her conquests online.

This simple use of mobiles and bluetooth could spark a worldwide phenomenon. And like SMS, bluetooth was designed for something quite different to bluejacking.

Unveiled in 1998, bluetooth was designed to replace cables between other mobiles as well as headsets, home computers and printers.

Bluetooth can transfer data within a range of 10 metres, but future versions could transmit up to 100 metres with a power boost.

Bluejacking is fairly simple. Turn your phone's bluetooth on and allow it to be "discoverable" by other bluetooth phones. Create a contact in your address book using your message as the name, with a message such as "you've been bluejacked!". Search for a bluetooth-enabled phones within range and send the contact to them.

But knowing what people are capable of, bluejacking could easily have a darker side than mere teenage pranks. Unsolicited messaging is unlikely to be welcomed and technically illegal. And without the filter of having to sign up to an SMS service, bluejacking would be an entirely unregulated and unregulatable means of communication. Similar to the internet, but unlike the internet, less than 10 metres away from where you stand.

The possibilities for sexual harassment, illegal commercial spamming and sheer annoyance are, unfortunately, endless, although it's possible to block anonymous messaging.

There is also the problem of accidentally sending your phone number with your bluejack message, exposing yourself to nuisance calls. But until more nefarious uses are discovered, bluejacking offers possibilities for relatively safe social interaction.

Mr Mike Grenville of 160 Characters, a UK's messaging industry body, even suggests that Bluejacking could be used to invite people to play mobile games with each other on crowded commuter trains, but virtually anonymously.

And you could see gaming commuters sooner than you think. Although right now, Forrester Research says only 9 per cent of mobiles in Europe have the facility. But, according to a new Frost & Sullivan report, Bluetooth devices in 2003 will double to 70 million units.

Of course, the 55 million text messages sent a day between people in the UK last June are hardly under threat from a technology which can only send messages 10 metres away. It would be simpler to just shout. But anecdotal evidence suggests bluejacking is taking off among teenagers.

A poll on mobile community Esato.com this month registered over 28 per cent of visitors as having bluejacked someone.

New businesses are emerging to take advantage of bluejacking, in particular.

TagText.com is a UK firm which is taking advantage of the ability to send images as well as text over bluetooth to create illustrated digital characters which teenagers can download to their mobiles and use for bluejacking. At the moment, the service is free but there are plans to start charging via premium rate SMS to download the characters.

The are also opportunities for so-called "viral marketing", allowing cutting-edge brands to circulate advertising.

But is bluejacking just a fad? SMS was dismissed early on by the analysts, who saw only its business applications. But it's the seemingly frivolous application which capture people's imagination.

If bluejacking really does go mainstream, people in theory will start to disable bluetooth on their phones for fear of harassment, leaving the bluejackers to harass each other.

But for a while it will be easy hunting, and perhaps new social connections will be formed, incentivising the transformation of bluejacking into something more worthwhile.