You can only send messages to people within a certain distance, and no-one knows that it's you who sent it.
You also need a Bluetooth phone to be able to send messages this way.
Because the message doesn't carry your name or mobile number it's fab for playing jokes on people, but it also means people can trick you too.
Until now it's been more expensive phones that have Bluetooth technology, but as the handsets get cheaper, bluejacking is sure to be on the rise too.
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