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How to make a key beeper that can be activated by a cell phone? Answered

Is there a device that that can be somehow activated by 'some' signal produces by today's cell phones (bluetooth, wifi, infra...) and then make a beep sound? Preferably it should be small, light, cheap, with low consumption of energy.

It should work as a beeper to find a thing that it is attached to more quickly. 

Any ideas?


The answer's fairly obvious:

Use another mobile phone.

But that isn't what you wanted is it?


Not exactly. What I want is basically what yokozuna suggested - something like this http://www.upager.com/ . However, instead of the device that activate it and make it beep, it should be a mobile phone

Yes, you'll have to use another mobile phone or a pager - something connected to a phone network.
But you want to do this without a mobile phone or a pager, yes?


If it's going to respond to a mobile phone, it has to BE a mobile phone. (Or a pager that you can set off by calling its number from your mobile phone, or a networked device that's controlled from a computer that can receive and respond to phone calls.)

Bluetooth is theoretically possible if you've got a smartphone or bluetooth-capable computer and are willing to write the software. Other than that, we're back to needing a phone again.

Yeah, it's theoretically possible to build something that will sniff the radio traffic and recognize that a particular phone has tried to connect. Possible, not practical.

It's called a pager. You get a contract where the pager is assigned a telephone number. When somebody calls that number, the pager will beep or vibrate, and display the number of a little screen. Set up your mobile phone so the pager's number is on speed dial.

There are plenty of commercial devices for such a thing like this one.  That's simply the first result of a google search for key beeper.

Right, but the question was how to make it the way that you can activate it with a mobile phone.