On the dial-pad, dial *3001#12345#*
Now hit Call! (Don't worry, it's not gonna charge you)
You have now entered 'Field Test mode'
This changes the bar-based signal indicator to a “proper” numerical figure. There are also menus to tell you all sorts of other signal information, but most (including me) will be hopelessly lost here
Explore the menus or just show it to your friends! :D
The creator of this guide has not included tools