Slashdot Mirror
Interesting Uses For Old GSM Mobile Phones?
Anonymous Coward asks: "Over the past few days, I was wondering if there is any use for old GSM mobile phones. The rate of development of these things is phenomenal, and phones seem to be becoming obsolete faster than PCs. They must have a fairly powerful processor if they are able to support real-time encoding with whatever codec (full rate, enhanced full rate etc.) they use for GSM. It seems like such a waste to throw these things away - anyone got any ideas?" How much work would it take to convert an old GSM phone into a two-way walkie-talkie?
Part of the problem is that while you might own the phone, you don't have a license to use the frequencies that it operates in. Changing the frequency would not be a simple thing.
Of course one could ignore the law.....if you're willing to risk it.
. Quit playing Monopoly with Bill. Switch to one of many non-Microsoft products today.
If you want to use them with a cellular contract, some phones such as Nokia are well enough understood that you can connect them to PCs, audio, or phone devices...and they can be used with analog devices, digital links, or SMS. Linux tools are available also for Nokias.
I don't know if GSM phones have protocols for talking directly with GSM phones. Now we'll hear from others...
In short, find the phone subscription with the cheapest monthly fee and install the SIM into your old phone. Then rig the old phone so that something happens when it rings. Every time you want this something to happen, just call the number. As the old phone never actually answers the calls, it costs you nothing!
In April 1997 we built a vodka dispenser out of an old GSM phone, a PIC microchip and a magnetic valve and installed it into a huge wardrobe. You would call a number and the wardrobe would set some LEDs flashing, play some music -- instant multimedia show! -- and dispense a glass of vodka. The whole shebang was then given away as a gift at a party and served happily the whole night, as long as we kept it topped up with vodka. :-)
We did it the cheap way; by opening the phone and soldering a cable from the buzzer to the PIC. Then we programmed the PIC to recognise the ring pulse. When the ring signal started, the PIC would wake up, do its magic and go back to wait mode. Very simple.
Sadly enough, people didn't really get the fact that it actually worked, they thought we just faked it. :-( Oh, the humanity... Also, we didn't think of documenting the project until afterwards. I know that there are a couple of photos floating around somewhere, but I don't know who's got them right now.
You must agree that this concept has some real hacking value. :-)
--Bud
Imagine you can use both a charger and a data-connector in your GSM-phone. Then lets program the phone to call you when it gets input from your car burglar alarm.
No more angry neighbours.
//Joachim