There is an interesting trick for your iPhone if you would like to see the signal strength as number instead of usual bars.
What you will see when you do this trick is a negative number indicating the decibels referenced to one mill watt (dBm) rather than a signal bar and is performed in the Field Test Mode.
Why you need this trick to see phone signal strength as number?
You can use this trick toread the numbers so that you can understand what is a good cell signal vs a bad one. This would come in handy, as an example, if you find yourself in a dead zone. It would be easier to track which area will allow you to make that important call.
Field Test Mode is a hidden feature on the iPhone which allows you to see technical details of the device, the most useful of which is the true signal strength displayed as a number rather than the traditional signal bars. It only takes a minute or two, and it’s easy to reverse back to normal, so try it out!
The numbers don’t follow a scale that makes much sense to normal people, but the lower the number (in other words, the more negative) the worse the signal, and the higher the number (less negative) the better.
- Anything above -80 is good, and would be considered full bars
- Anything below -105 is bad, and would be considered few bars
For example, a signal number of -105 is considerably worse than a signal of -70. You’ll generally find that anything approaching -100 or lower is fairly bad reception, while anything above -80 is usually good, and if you tap the number signal it’s usually shown as full bars.
The full range of the signal numbers extends from -40 to -120, with -130 being a nearly impossible number to see because it means no reception, and -40 would be about the strength you’d get being right alongside a cell tower.
Once you get the hang of reading the numbers, you’ll find it’s much more accurate, and it becomes easier to predict when you may drop a call or start to get a bad signal or connection, which creates the weird artifacts and sounds on phone calls, often before it starts to cut out or even drop completely. That typically starts happening around -110 or so, before dropping the connection or call completely if it hits -120 to -130.
How to See iPhone Signal Strength as Number
Dial *3001#12345#* and hit call
You will enter the Field Test Mode and see the signal strength as a number.
Press the home button and you will be out of the field test mode.