By Mark Ward
BBC News Online technology correspondent
Phone owners now have something else to do with their handset: bluejacking.
Are you being bluejacked?
This involves sending anonymous text messages to other phone users via Bluetooth short-range radio.
Bluetooth works over a range of about 10 metres and phones fitted with it can be made to search for other handsets using it that will accept messages sent to them.
Mobile phone buffs have been bluejacking for months but it now looks set to become much more widespread.
Bluetooth was created as a way for mobile phones to easily connect to other handsets as well as devices such as headsets, home computers and printers.
The radio technology only used to appear on more expensive phones but is rapidly becoming a standard feature in all kinds of handsets.
Research carried out for the Bluetooth special interest group, which oversees the development of the technology, suggests that more than one million Bluetooth-enabled devices are being shipped every week.
The idea of bluejacking originated on the message boards of the Esato website that is a favourite of many owners of SonyEricsson phones.
Now a regular bluejacker has set up a site to tell others how to do it and to swap tips and stories about the phenomenon.
HOW TO BLUEJACK
Turn Bluetooth on
Ensure your phone is discoverable by other Bluetooth devices
Create contact using your message as the name
Choose to send this contact via Bluetooth
Phone searches for Bluetooth-enabled phones within range
Pick a victim from the phones within range and send the contact to them
"I came across the idea of bluejacking at an online discussion forum and it immediately struck me as a fun thing to do," said Ellie, who set up and runs the bluejackQ (Bluejack You) website.
She said the "priceless" expression on the face of her first victim as he tried to work out what was going on has turned her into a regular bluejacker.
"This, mixed with not knowing whether the victim will react in an amused/confused or negative way gives me an adrenaline rush," she said.
Bluejacking involves creating a contact in your phone's address book using the message you want to send as the name for the entry.
On most Bluetooth phones it is possible to send this contact as a message or electronic business card.
Choosing to send this contact via Bluetooth makes a phone search for other Bluetooth-enabled devices nearby.
The contact bearing its message can then be sent anonymously to any Bluetooth phones within range.
Bluejacking works underground too
To be bluejacked you must make sure your phone can be discovered by other Bluetooth devices.
The bluejacking craze seems to be catching on as numbers of page views of the bluejackq site are now averaging 8,000 per day.
It might be helped by the fact that sending messages this way is free.
Good spots for bluejacking are anywhere crowds of people gather such as railway stations, airports, pubs or busy shopping streets. Ellie said that mobile phone shops usually yield a few targets too.
Although Bluetooth is included on many phones, many people have it turned off because they do not use it.
However, bluejacking expeditions by BBC News Online technology staff have shown that in any decent-sized crowd, such as on a tube train or train platform, usually reveals several Bluetooth phones.