How can you find the signal strength of your cellphone?

To find the signal strength of your cellphone, put the phone in the field test mode. If you are using an iPhone, open up your phone app, input the code "*3001#12345#*" and hit the call button to measure the signal strength.

While in the field test mode, you cannot see bars at the top left-hand side of your mobile phone. A negative number replaces these bars instead. These negative numbers can range between -40 and -130. The lower the negative number gets, the better the signal your phone has. A phone is at its best signal strength when it reaches -40.