Field Test Mobile Phone Signal Strength

Want to know if’s mobile phone signal booster works for you? Do a simple field test on your mobile phone by using your mobile phone to check the signal quality outside your house.

Step 1 – Go outdoor your home or office with your mobile phone
Step 2 – Disable WiFi connection on your mobile phone, then you to see what network you’re connecting to (2G, 3G, 4G, LTE, etc.).
Step 3 – Take a note of signal bars and the symbol in the status bar of your mobile phone and compare them with the below chart

Symbol Mobile Networks Voice Call Internet Speed Email & Notification Video
(General Packet Radio Service)
Yes 50Kbits/s Yes No
(Enhanced Data GSM Evolution)
Yes 100Kbits/s Yes No
3G Third Generation
also known as UMTS / WCDMA / CDMA2000
Yes 2Mbits/s Yes Yes
(High-Speed Packet Access)
Yes 10-100Mbits/s Yes Yes
4G Fourth-generation or Long term evolution
also known as LTE or WiMax
Yes 100Mbits/s+ Yes Yes
No Symbol If signal bars get more than 1 bar
you can use voice call
N/A No No No

You can read signal bars followed by carrier name and network symbol in your mobile phone, which usually maxes 5~8 bars. To measure the mobile phone’s signal reception in exact decibels instead of bars or dots, you can follow step 4 to enter Field Test Mode in mobile phones.

Step 4 – In iPhone — Go into the Phone app and switch to the Keypad. Dial *3001#12345#* and press the Call button.
It will launch the Field Test Mode app on your mobile phone, and you will see a negative number of decibel signal strengths in the left-right corner of the screen.

In the latest iOS system, it says “Back to Phone” in the top left corner. To take decibel signal readings on the latest iPhone, you need to replace signal bars with numerical signal strength. Once in Field Test Mode, press and hold the power button until it shows “Slide to Power Off,” then release it. Then hold the Home button until returned to the main app screen. Now you will see numerical signal strength in iPhone; tap signal numbers you can switch to signal bars. To exit Field Test Mode, you need to reload Field Test Mode and exit it via the Home button.

Step 4 – In Android — Go to “Settings > About Phone,” and numerical signal strength will be available on either network or status, which depends on the phone model. You can also use apps to show signal strength in decibels in Android phones.


1) The numerical value of 2G / 3G / 4G H+ networks is RSSI standard, which is the Received Signal Strength Indicator. LTE network is RSRP standard, which is Reference Signal Receive Power. Hence, you need to turn off LTE on your mobile phone before entering Field Test Mode.

2) Decibel signal strengths will be negative 2~3 digits.  The unit of measurement is dB. If your phone shows a number such as 98, the actual signal strength is -98dB. The closer the number is to zero, the better the reception, so -90dB is a stronger signal than -100dB.

Easy table of signal bars and decibel signal strengths

Signal Bars iPhone Mobile Nokia Phone
5 > -85 dBm > -91 dBm
4 -85 ~ -90 dBm -91 ~ -101 dBm
3 -90 ~ -95 dBm -101 ~ -103 dBm
2 -95 ~ -100 dBm -103 ~ -107 dBm
1 -100 ~ -105 dBm -107 ~ -113 dBm
0 < -105 dBm < -113 dBm

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