According to an email urban legend, certain models of Nokia phones have built-in radar detector that you can activate via secret code. Obviously this can't be true. But what I'm curious about is if a radar sign actually will appear on certain models if you follow these instructions. I could imagine bored engineers programming this in as a joke. Since I don't have access to a Nokia phone I can't test it out. Here's the email:

Nokia Speed Trap Detector
The settings for radar speed traps detector.
Your Nokia cell phone can be programmed to pick
up radar speed traps, when programmed your cell
phone picks up the radar and alerts you on the
message alert tone. ( Doesn't work with Nokia
7110! )

1. Enter your menu
2. Select settings
3. Select security settings
4. Select closed user group
5. Select on
6. Enter 00000
7. Press ok
8. Clear back to normal, within a few seconds
your phone will display a radar sign with five
zero's next to it. It is now activated.

Unfortunately only Nokia phones have this
function. Cell info display needs to be de-
activated. Settings -> Phone Settings -> Cell
Info display
Each time you turn off your phone, or even each
time you loose contact with your carrier, you'll
have to activate it again... It is done by steps
1 through 5, but the number (00000) will be
already on the field as default.