This is a story about the use of technology used by both sides in the ancient and ongoing battle between teenagers and adults.

It starts with a clever bit of entrepreneurship. A company called Compound Security Systems developed what amounts to a "teenager repellant" designed to drive kids away from malls, stores and other places where teens congregate and annoy paying customers. Called the Mosquito, the electronic box produces an ultra-sonic tone within the audible range of children and teenagers, but just above what most people over 25 can hear -- somewhere in the 18 to 20kHz range.(Note: This blog entry is an excerpt from this week's Personal Tech Pipeline e-mail newsletter. Columns are normally exclusive to the newsletter, and not posted anywhere online. If you'd like to subscribe, please go here.)

The Mosquito apparently works well -- especially as it gets more annoying the longer one is exposed to it. So hanging out within range of one of these things becomes increasingly unpleasant for those who can hear the tone it produces.

Realizing that the Mosquito generates a tone only teens can hear, some enterprising teen recorded the tone, and used the recording to make a cell phone ringtone called Teen Buzz -- again, that only teens can hear. The ringtone has been passed from teen to teen via message boards and P2P networks.

As cell phones are banned in most high school classrooms, some teens are using Teen Buzz as a kind of mocking revenge (putting a cell phone on vibrate mode is a lesser act of rebellion than a ringtone only other teens can hear). When a Teen Buzz cell phone rings at school, everyone in the class can hear it clearly -- except the teacher. The phone rings, the students all laugh, and the teacher doesn't know what's going on.

Now the story comes full circle. Seeing that a pirate version of their tone is gaining popularity, Compound Security Systems has decided to give away a high-pitched ringtone of their own, presumably as an attention-getting bit of guerilla marketing. They call it Mosquitotone, and it's currently available in the UK -- and soon all around the world.

Can you hear me now?