Enable Cellular Signal Strength Indicator on iPhone

How many times have you glanced at your signal strength on your iPhone and been caught out by what it says ?  Thanks to a hidden feature you can now change your signal bars to numbers (dBm) for easier reading.  It’s a feature that has always been on iPhone’s running iOS 4.1 or later, it doesn’t require any jailbreaking to access and you can change the numbers back to bars whenever you want to.

Steps to Enable Field Test Mode :

field test indicator - iphone 5 signal strength

  1. Open your phone app and dial *3001#12345#*
  2. Tap on the call button and you will enter Field Test Mode. At this point notice that your signal strength bars have changed to a number.
  3. Hold down the Power off button until the power off slider appears but do not power off the phone.
  4. Release the power button and hold on the Home button until the Field Test App shuts down.

There you have it, it’s as simple as that, your iPhone is now displaying your signal strength in numbers. If you want to flip between bars and numbers just tap on the indicator and if you want to disable the feature follow the steps below .

Steps to Disable Field Test Mode :

  1. Dial *3001#12345#* and press call button to enter Field Test Mode again
  2. Press your Home button once. This will revert the indicator back to bars and you will be unable to see the numbers.

A word about the numbers displayed – you will notice that they are all negative numbers. This is the normal way of displaying decibels which is what these numbers are. To read them you can discount the negative sign if you wish but remember that, this way, the lower the number, the better the signal.  The best way to understand the numbers is this :

  • Anything that reads above -80 is considered a good signal and akin to having full bars of signal strength;
  • Anything below -100 is a bad signal and very few bars – you can check this by tapping on the indicator to switch between the 2.

The full range runs between -40 and -120 – this number is rarely seen as it is basically no reception at all.  This is a great feature if you find yourself in a dead zone as it will help you to find a better signal strength.