The BlackBerry, like most other mobile phones, uses a bar graph to indicate the current signal strength of your cellular network. If you see five bars on the screen of your BlackBerry smartphone, the network signal strength is excellent. If it shows a lower number of bars, the signal may be insufficient or poor.
The bars give an approximate idea of the signal strength, but just by looking at them, you won’t be able to determine minor fluctuations in the signal that may occur when you move across different rooms in your house or accidentally cover the cellular antenna of the phone with your hands.
However, there is an easy ‘cheat code’ with the help of which you can determine the actual network signal strength on your BlackBerry.
BB cheat code
Hold down the ALT key on your BlackBerry and type the letters NMLL in the same sequence — the bar graph indicating signal strength will convert into real numbers indicating the exact strength in dBm.
You can key in the same sequence to return to Bar Graph mode. The signal range should be anywhere between –40 dBm and –100 dBm for you to send and receive data/ calls without hindrance. The higher the number on the screen, the better the signal strength on your phone is.