Originally Posted by
emscapt47 How do you put it in field test mode?
Field Test Mode
*3001#12345#*
(Always show Decibels instead of Dots)
If you want your iPhone to always display numerical signal strength instead of signal bars, you can perform the following process. Once in Field-test mode (accessed by entering and dialing the code above), hold down the power button until you see “Slide to Power Off”, then release it. Then hold the Home button until you’re returned to your main app screen. You’ll now see your numerical signal strength while you use your phone, and you’ll be able to tap the signal numbers to switch to signal bars, and vice versa. To exit this permanent field-test mode, simply reboot the phone or re-load Field Test Mode and exit it via the Home button.