Hidden cell phone features - some obvious, some fiction

[Buckeyefan 1]

Some of you may already know this, but most cell phones have some cool features most of us are unaware of. Try these numbers out:

Dial 112 for an emergency worldwide. This number works even if the phone is locked.

You cell phone can pass a signal to unlock your car IF someone on the other cell phone has the other key fob and hits "unlock" next to the phone. Put your cell phone up to the locked car, and it should unlock. This works nicely if you and the wife have key fobs on each keychain for the same cars. Chances are if you locked your keys in the car, your cell phone is probably in there also. Hopefully the car isn't still running.

Some phones have a reserve battery. Mine does not - or I can't get this number to work (it's a Nokia). If the battery is low, try hittin *3370# to tap into the reserve battery.

*#06# brings up your serial number on your phone. Write it down. If your phone is ever stolen, call the provider and give them this serial number. They can disable the phone completely. This renders the phone inoperable - even if the memory/sim card is swapped out.

 

[j_garcia]

911 should work also, even if the phone is locked.

There are also codes that you can punch in that will download and update your phone to the latest software ver. They are different depending on your carrier and system I'm sure.

 

[Audioholics]

Snopes, people: http://www.snopes.com/autos/techno/keyless.asp

You can't unlock your car with a cell phone-relayed keyfob command.

 

[warhummer]

Snope article smells a little fishy

I haven't actually tried this one, but now my curiosity is peaked. The fact that the key fob and the cell phone operate on two different frequencies shouldn't matter (grabbing deep into my fuzzy EE knowledge here). The cell phone frequency is merely a carrier frequency. By the article's logic, you wouldn't be able to hear a human voice on a cell phone since it's emitted at a much lower frequency than the cell phone transmission.

Now for the really geeky part. Look at the FCC ID code on the back of your key fob. You can type this into the FCC's website and find out all sorts of useless data.

 

[10010011]

I haven't actually tried this one, but now my curiosity is peaked. The fact that the key fob and the cell phone operate on two different frequencies shouldn't matter (grabbing deep into my fuzzy EE knowledge here). The cell phone frequency is merely a carrier frequency. By the article's logic, you wouldn't be able to hear a human voice on a cell phone since it's emitted at a much lower frequency than the cell phone transmission.

Now for the really geeky part. Look at the FCC ID code on the back of your key fob. You can type this into the FCC's website and find out all sorts of useless data.

Remote keyless systems consist of a key fob transmitter and a receiver inside the vehicle. They most commonly use a frequency of 315MHz in the the U.S. and Japan, and 433.92MHz in Europe. Europe has also opened up the 868MHz band to accommodate the growing demand for remote keyless entry systems.

Sorry Snopes is right (as always) Your cell phone can not take in input of 315Mhz through its microphone and send it to another phone to be played back on its speaker.

Besides On-Star equiped card have more than a cell phone in them. It is a cell phone based modem that also has a serial connection to the cars on board computer. Thats how they send the signal to unlock it.

 

[jonnythan]

I haven't actually tried this one, but now my curiosity is peaked. The fact that the key fob and the cell phone operate on two different frequencies shouldn't matter (grabbing deep into my fuzzy EE knowledge here). The cell phone frequency is merely a carrier frequency. By the article's logic, you wouldn't be able to hear a human voice on a cell phone since it's emitted at a much lower frequency than the cell phone transmission.

Now for the really geeky part. Look at the FCC ID code on the back of your key fob. You can type this into the FCC's website and find out all sorts of useless data.

Uh....

Human voice is transmitted by using a microphone that digitizes the signal and transmits it via the antenna.

The microphone picks up sound, not electromagnetic waves from a car alarm remote. And the speaker on the phone at the car vibrates to produce sound, not radio frequency EM waves.

 

[j_garcia]

Uh....

Human voice is transmitted by using a microphone that digitizes the signal and transmits it via the antenna.

The microphone picks up sound, not electromagnetic waves from a car alarm remote. And the speaker on the phone at the car vibrates to produce sound, not radio frequency EM waves.

But don't most keyless entry systems/alarms work on RF? I wouldn't think that could be transmitted via a phone.

 

[jonnythan]

Radio frequency, RF, refers to a specific section of the electromagnetic spectrum. RF waves are EM waves, just like light, X-rays, gamma rays, infrared rays, etc are EM waves.

http://www.yorku.ca/eye/spectrum.gif

Sound is, obviously, a physical pressure wave that must be turned into an electromagnetic wave for transmission. This is done through the use of the microphone to turn it into an electric signal and a transmitter to turn it into an EM wave.

 

[j_garcia]

I understand what the RF band is, and since the band is so high, I suspect that even a really good pair of phones won't transmit the signals in that range.

I don't want theory, I want someone to try it.

 

[jonnythan]

They're different types of signals entirely. An RF signal isn't a high frequency sound wave. RF is the same type of wave as light. It's an electromagnetic wave. Sound is a pressure wave transmitted by a medium such as air, glass, or wood.

A microphone can't pick up any type of electromagnetic wave, no matter the frequency. A microphone picks up vibrations in the air.

 

[jonnythan]

Let me put it this way:

Sending an RF signal through a phone is physically identical to sending a beam of light through a phone. So, unless you can help out someone in the dark by shining a flashlight into the microphone of your cell phone, an RF signal won't transmit either. The only difference between light and radio waves is that light has a lower frequency.

 

[BMXTRIX]

I can totally see some idiot coming along and saying: "No, really... It works! My car was in my driveway and my friend was in the garage with the garage door down. He couldn't see me at all, and we tried it... It totally worked!"

People, as it turns out, often are not very bright.

 

[warhummer]

Uh....

Human voice is transmitted by using a microphone that digitizes the signal and transmits it via the antenna.

The microphone picks up sound, not electromagnetic waves from a car alarm remote. And the speaker on the phone at the car vibrates to produce sound, not radio frequency EM waves.

Thanks for the physics lesson! I wasn't actually saying that this would work, just commenting on how the Snopes article described it. Depending on what type of microphone was used, you could pick up ultrasonic frequencies and transmit them.

If you really want to get in the weeds, EM waves do have mass and they can impart momentum on an object. Solar wind baby!

 

[Jack Hammer]

Let me put it this way:

Sending an RF signal through a phone is physically identical to sending a beam of light through a phone. So, unless you can help out someone in the dark by shining a flashlight into the microphone of your cell phone, an RF signal won't transmit either. The only difference between light and radio waves is that light has a lower frequency.

That's basically what I had figured. The whole concept of transmitting a radio signal through a phones micropone and having it 'play' out a speaker sounds like BS to me, good BS, but still BS. If it were possible, the only idea I can come up with is the phones antenna, not the mic, picks up and transmits the signal. For the record, I know almost nothing about the topic in general.
But I like J_Garcia's idea of having some one try it, just to be scientific.

Jack

 

[Tsunamii]

This one comes up every few years. It would be cool if it did work but alas im stuck with just hacking elevators insted Press the close door button along with the floor you are going to (and if you are lucky to be in one of the 9-% of eleveators it works in) and skip every floor that has been selected in between. For those in Boston this does not work at the Pru...

 

[Audioholics]

So, unless you can help out someone in the dark by shining a flashlight into the microphone of your cell phone

omg this totally works!!!!

 

[j_garcia]

But I like J_Garcia's idea of having some one try it, just to be scientific.

Jack

LOl, I'll send this one to Myth Busters