If you wish to see numeric signal strength on your iPhone instead of bars then through guide below you will learn that what you have to do to get that on your iPhone.
Enable Numeric Signal Strength on iPhone
Dial *3001#12345#* on your iPhone through keypad and tap on “Call” button
Immediately “Field Test” app will get open and you can observe a negative numeric value at the place of signal bars in left upper corner of your iPhone screen.
Note: Now, when you exit “Field Test” app on your iPhone, numeric equivalent of signal strength will again toggle to bars, so if you want to make bars permanent to numeric value then continue with next step without getting exit from Field Test on iPhone.
Press and Hold “Power” button until “Slide to power off” bar display, but do not Turn Off your iPhone
Press and hold “Home” button until it takes you back to the home screen and that’s it
Now, you can stick with numeric signal strength on iPhone which you can toggle to bars as well just by tapping on it and vice versa.
Just use this tip to enable numeric signal strength on iPhone and write your experience in comments.