Here is a nice way to get into the Apple iPhone field test menu. This is where you will figure out the signal strength of your phone.
Dial on your phone Press *3001#12345#*
Qualcomm
Rx AGCO signal strength
>-70 = Excellent
-70 to -85 = Good
-86 to -100 = Fair
< -100 = Poor
Intel Chip
looking for rsrp0 mode
>-90 = Excellent
-90 to -105 = Good
-106 to -120 = Fair
< -120 = Poor
-125 = No Signal
Dial on your phone Press *3001#12345#*
Qualcomm
Rx AGCO signal strength
>-70 = Excellent
-70 to -85 = Good
-86 to -100 = Fair
< -100 = Poor
Intel Chip
looking for rsrp0 mode
>-90 = Excellent
-90 to -105 = Good
-106 to -120 = Fair
< -120 = Poor
-125 = No Signal