Every wonder if the signal bars in the upper corner of your iPhone are telling you the truth or not?
Well, there is a secret number that iPhone users can dial to see how much service their phone is really getting. Dialing “ *3001#12345#* ” switches the signal bars to negative numbers, which in turn represents the exact signal rather than just a range — the higher the number, the stronger the signal.
A number between -40 to -70 is equivalent to a 5-bar signal while -102 to -120 is the same as a 1-bar signal.
The bars on your iPhone actually represent a signal range, not an exact signal.
First, you’ll need to access a hidden app on your phone called Field Test Mode. To do this, you’ll need to open up your Phone app and dial the following number, *3001#12345#* , including the asterisks and hashtag, and tap “Call.”
This opens up Field Test Mode, which is mostly filled with menus of cell signal jargon that you don’t need to worry about. What you’re interested in is the tiny number in the upper left-hand corner of your iPhone, which should have replaced those cell signal dots.
Here, for example, my iPhone is showing my cell signal to be -59.
While that number can vary anywhere from -40 to -130, it will always be negative, and the closer that number is to zero, the better your cell signal, according to OSX Daily. The best signal you can get would be -40, and no signal at all would be -130.
To exit Field Test Mode, you can simply tap the home button and you’ll be brought back to your iPhone’s home screen, no harm done.
Now, you can always repeat this process to enter Field Test Mode and see your true cellular signal, but if you’d like the ability to always check that number without going through that hassle, you can set things up so your iPhone will display both numbers if you just tap the signal dots in the future.
To be able to peek at your true signal strength number you need to get back into Field Test Mode by redialing *3001#12345#* and tapping “Call.”
You’ll be brought to the Field Test App, but instead of using the home button to exit, hold down your iPhone’s power/sleep button until it shows the “Slide to power off” screen and then hold the down your iPhone’s home button, which will force quit Field Test App.
You’ll be back to your iPhone’s homescreen, but this time you should notice that your signal strength number has replaced your signal strength dots.
If you tap that number, you can switch between the two as you see fit.
To undo any changes you made, simply repeat the steps to get into Field Test Mode and tap the Home button to exit the app, and everything will revert back to normal.
Check out the video below to see just how easy it is to see your phone’s true signal strength and switch back and forth from bars to numbers.