View Your iPhone’s Numeric Signal Strength

Starting way back with iOS 4.1 and continuing through the latest version (6.0.1 at the time of this writing), Apple has enable a hidden “Field Test” mode which allows users to, among other things, see the exact signal strength of their cellular connection instead of the arbitrary bars which, as we all know, don’t always perfectly indicate how poor of a signal we’ve actually got. Simply by entering the Field Test mode, you can see this numeric value and get a feel for how good or bad your signal might be. Getting that number to stay there in place of the bars is a bit trickier, but still quite easy to accomplish. Here’s how.

  1. First thing’s first, you’ll have to open up your Phone to make a call, tap on the Keypad, and enter in the following: *3001#12345#*. As soon as you tap Call, it will open up the Field Test mode.
    iPhone Field Test Code
  2. As soon as the Field Test screen opens up, you’ll notice that instead of the standard reception bars in the upper left-hand corner of your screen, you’ve got a negative number indicating the decibels referenced to one milliwatt (dBm). Keeping in mind that these are negative numbers, anything “greater” than about -100dBm is decent reception, with -50dBm being perfect. Anything “below” about -110dBm and you can safely assume there’s a good chance you’ll drop the call and you might have trouble with data.
    iPhone Field Test
  3. Now that you know how to read the new number in the corner of your screen, the tricky part is getting them to stay there once you leave the Field Test. Tap on the screen where the numbers are so that it switches back over to the bars. Once you’ve done that, hold down the Sleep Button on your phone until the “slide to power off” screen comes on. Instead of turning the phone off or hitting cancel, just hold down your home button for several seconds. It’ll cancel out of everything and return you to your home screen, but now it will show the numeric reception value instead of the bars.

That’s it! Unless you go back in to the Field Test and tinker with it again, it should permanently give you access to the numerical signal strength of your iPhone. You can even tap on the numbers whenever you’d like to go back and forth between the numeric value and the bars.

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