How to get a true reading on iPhone signal strength

Have you ever wondered why your email won’t load even thought you have a signal? This often frustrates me to no end and it’s not just that I have AT&T’s spectacular cellular coverage (take this with a heavy dose of sarcasm). Well if you ever wanted to know what your signal was beyond that depiction of progressively larger bars in the top left corner of your screen, you can now find out! follow the instruction below to enter a “Field Test Mode” on your iPhone. This process can be reversed if you don’t want to keep it and so far I know that it works on the iPhone 4 and 3GS.

UPDATE: it seems that if you are on a firmware prior to 5.0 this will not work. Make sure you update then try this.

 1. from the phone app dial *3001#12345#* then press Call.

2. You will now see a Field Test menu show in the screen and you will see the signal bars are now  represented in a number form. If you want to just exit Field Test mode just press the Home button. If  you want to keep this active-

3. Hold the Power (sleep/wake) button until the “slide to power off” screen shows on the phone but do not power down the device.

4. Press and hold the Home button until the home screen shows.

This will enable the signal to show as numbers and the lower the number the better your signal is. If you would like to see the bars or toggle back and forth just simply tap the signal area of the screen.

If at some point you want to disable this just dial *3001#12345#* and press call

2. Press the Home button once