cell-into-radio

[bigbadbill411]

A challenge to the nerds...
Is there a way to modify a cell phone to skip the tower and communicate to another call phone? Turning it into a real walkie talkie-
Is it a big secret?
Bill

[Chris Smith]

They already have the "Walkie Talkie" option in some brands.

[josmith]

YOu can take two cordless phones,hook the bases together and use them as portable radios.
The walkie talkie function of a cell phone still uses the network.
Since a cell phone looks for it's network to opretate. I doubt that it would be practical to re program it for phone to phone communication.

[dyarker]

Absolutely right josmith. And, not to mention that the FCC will be called by the local cell phone carrier when modified phones interfer with paying customers calls.<p>No big secret; about anything it possible with enough effort. The code in cell phone's processors is locked to keep users from making illegal changes, and to keep competiters from stealing it. So no secret, it's just not worth talking about. Go with Chris Smith's or josmith's suggestion.<p>Hooking two cordphone bases together is clever. But it will probably need talk battery in series to work. Adding ringing is a little more involved, but not difficult; depends on cordless phone model.<p>Cheers,

[bigbadbill411]

Its Bigbadbill here,
I believe you, but Im a little dissapionted.
Im suprised that with all the old cell phones lying around no one has spent the time on some good "recycling" programs.<p>Thank you so much for posting, Id be so jealous to find that every body else was doing it.

[Bernius1]

If they Rx'd & Tx'd on the SAME freq, you could change the X-tal, or some SMD cap's & drop it into an open freq.range. But they Rx &Tx on different frequencies, so it'd be very difficult to match them.

[bigbadbill411]

There is hope then?
What is the xtal, does changing it require a pc connection, or is it a matter of changing the circuitry a little?<p>???What about bypassing part of the circuitry and running it through a crystal? 49.860 like the remote control cars or something?

[josmith]

There are places that take old cell phones for re-use as emergency phones for people with special needs. Much better idea than distroying it by tying to hack the unhackable.
Take advantage of the new FRS and GMRS radios they're cheap,they work good and they're Legal.

[bigbadbill411]

Thanks mr smith, say hello to the man for me.

[jollyrgr]

Back in the days of the "Bricks" (mid to late eighties) there was a way to do this. I do not know the specific models but there was a way to put the phones into a "zombie" mode. I remember being at a flea market where these phones were being sold on a weekly basis but never learned the "secret" models being used or the programming codes. The sellers were eager to sell them and they had plenty of buyers. Even though smaller phones were available at the time. There was something special about certain models of bricks but I never could locate information on how this was being done.<p>What these guys did was to put the phones into PROGRAM mode. They then keyed in test sequences to tune the receive and transmit channels, unmute the speaker, and engage the transmitter. I watched as one of the guys "in the know" helped a friend pick out a phone. This was all done with the key pad and could be done in a moment. The guy that "knew the secret" picked up a phone off a sellers table, hit a few keys on the phone and soon you could hear static coming out of it. He then took his phone, hit a few buttons, and you could hear the squelch of a received FM signal replace the static. When he talked on his phone, his voice came out of the phone for sale. He then handed the phone to his friend and listened to his phone. He confirmed the newly programmed phone was transmitting as well.<p>I don't know if they were using the cell tower as a repeater or if they were using the phones in "split" mode. (In other words they were setting one phone to receive on frequency A and transmit on frequency B then having the other phone receive on B and transmit on frequency A. This would be a full duplex communication.) I do not believe that they were using the towers as static was coming out of the first phone until the other guy started transmitting. If they were "pirating" the towers somehow the first time the phone was unmuted, there would not have been static.<p>Maybe I missed some of the nuances of this procedure but I know it was being done without placing an actual call. If anyone knows how this was done, what brand or model phone was being used, or other knowledge of this trick, please post or send me a private message. There were a number of people that knew how to do this and could be seen using these at the flea market. But I never could figure out how it was done.