Every mobile device has different algorithms for selecting bars and the method of putting your phone into Field Test Mode. Placing your phone into Field Test Mode will allow you to view raw signal strength, as demonstrated in the video above. Raw signal is the only way to get true signal strength readings from most smartphones. Below are updated instructions to the most popular mobile brands.
Apple
Please note that Field Test Mode is not compatible with iPhone's that have a Qualcomm chipset (i.e. some Verizon and Sprint Phones).
iOS 10.3.1 and newer
LTE
Dial *3001#12345#*
Select “LTE”
Select “Serving Cell Meas” signal strength will be displayed as “RSRP0”
UMTS
Dial *3001#12345#*
Select “UMTS”
Select “Serving Cell Meas” signal strength will be displayed as “RSCP0”
iOS versions OLDER than 10.3.1
- Dial *3001#12345#*
- Hold the Power/Lock button until you see “Slide to power off”. Do not power off, but release the power button.
- Hold the Home button until the phone goes back to your home screen. At this time you should now see your raw signal strength instead of bars on the top left of your handset.
- To go back to bars, dial *3001#12345#* and tap the home button to Exit Field Test Mode.
Most Android Devices
- Go to Apps
- Settings
- General
- About Device
- Status
- You will find the Signal Strength on this screen
Samsung
- Dial *#0011#
- The Signal Indicator will be displayed as RI or RSRP.
