Have you ever been doorbell ditching before? The point of the prank is simple: Sneak up to someone’s front door, knock loudly or ring the doorbell, and, instead of greeting whoever answers the door, run away and hide somewhere nearby. The joy of doorbell ditching is, of course, reveling in the homeowner’s confusion and rolling with laughter under the security of his nicely trimmed bushes. Although the game might get you in a bit of trouble if you happen to incite the ire of a cranky neighbor, it’s mostly a harmless joke on par with a prank phone call.

For more technically inclined pranksters with access to Bluetooth technology, however, there’s the digital version of doorbell ditching and prank phone calls: Bluejacking. A kind of practical joke played out between Bluetooth

Bluetooth technology operates by using low-power radio waves, communicating on a frequency of 2.45 gigahertz. This special frequency is also known as the ISM band, an open, unlicensed band set aside for industrial, scientific and medical devices. When a number of Bluetooth devices are switched on in the same area, they all share the same ISM band and can locate and communicate with each other, much like a pair of walkie talkies tuned to the same frequency are able to link up.

Bluetooth technology users take advantage of this ability to network with other phones and can send text messages or electronic business cards to each other. To send information to another party, the user creates a personal contact name in his or her phone’s address book — the name can be anything from the sender’s actual name to a clever nickname.

Bluejackers have devised a simple technique to surprise their victims: Instead of creating a legitimate name in the address book, the bluejacker’s message takes the place of the name. The prank essentially erases the “from” part of the equation, allowing a user to send any sort of comment he wishes without indentifying himself.

For instance, if you’re sitting in a coffee shop and notice a fellow Bluetooth user sitting down to enjoy a cup of iced coffee, you could set up a contact under the name “Is your coffee cold enough?” After choosing to send the text via Bluetooth, the phone will search for other enabled Bluetooth devices; selecting one will send the unsolicited message to that device. A bluejacker’s crowning moment comes, of course, when the victim receives the message and expresses a mild mix of confusion and fear that he’s under surveillance.

Bluejacking is imprecise, however. Searching for other Bluetooth-enabled hardware might turn up a list of devices labeled with a series of numbers and letters. Unless the bluejacker’s target has chosen to publicly identify his or her phone, or it’s the only Bluetooth phone in the area, the bluejacker may have a hard time messaging his or her target on the first try.

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