If you are a numbers person, you may like this iPhone hack that replaces the five dots in the upper-left corner of your iPhone that indicate the strength of your cellular signal with a numerical value. It does not require you to jailbreak your phone -- all you need to do is jump in and out of the hidden Field Test mode. Here's how:

1. Open the Phone app and from the keypad dial *3001#12345#* and then tap the call button. This will take you into Field Test mode.

Screenshot by Matt Elliott/CNET

2. Once in Field Test mode, you will see a negative number instead of the five dots in the upper-left corner. The closer to zero, the stronger your signal. As a rule of thumb, according to CNET's own Marguerite Reardon, "around -113 decibels is on the low end of the signal bar range, and around -50 decibels is on the high end." When I tested this hack, I had three dots for signal strength, which equated to a -100 decibels.

If you press the Home button to exit Field Test mode normally, the dots will return. We want to keep the numbers around, so instead of hitting the Home button, hold down the power button until the Slide to power off message appears and then release the power button.

Screenshot by Matt Elliott/CNET

3. From the power off screen, hold down the Home button for roughly 5 seconds until you exit Field Test mode. The signal strength numbers will remain and you can toggle between the numbers and the dots by tapping on them.

Screenshot by Matt Elliott/CNET

To reverse course and get rid of the signal strength numbers, go back into Field Test mode as you did in step 1 above and then simply hit the Home button to exit Field Test mode. When you return to your home screen, the familiar five dots will greet you.

Editors' note: This story was originally published on August 7, 2015, and has since been updated.

(Via WonderHowTo)