HOW TO: Enable Numeric Signal Strength On Your iPhone

Learn how simple it is to enable numeric signal strength on your iPhone

Look up at the top left corner of your iPhone… You see those little bars? As you should be aware by now, these vertical bars are Apple’s way ( Apple didn’t invent those bars – but they probably have a patent on it – but we’re talking about the iPhone now ) of representing something as complicated as a reception meter in a way a layman should understand. While this representation works for most users, it’s terribly inaccurate, and frankly doesn’t present much information.

What you may not be aware of however is that starting with iOS 4.1 Apple included a hidden app called “test app”, then when opened enables a cool db meter where your traditional signal bars would be.

Jump over the break to learn how to enable numeric signal strength on your iPhone…

1. Open the and tap on Keypad

2. Type *3001#12345#* and then tap on Call

3. As soon as you tap the Call button, the Field Test app will open. You’ll notice that instead of the standard reception bars in the upper left-hand corner of your screen, you’ve got a negative number indicating the decibels referenced to one milliwatt (dBm).

The problem is that, as soon as you tap that Home button to exit the Field Test app, your signal will be back to being displayed via the standard reception bars. So let’s see how to make the numeric display ‘stick’.

4. While in Test Field app, hold down the Sleep/Turn Off button until the Slide to power off screen comes up. Now, instead of turning the phone off, hold the Home button for a couple of seconds until it will return you to the Home Screen.

5. That’s it, now your signal will be displayed numerically. You can tap on it to switch between the numeric and bars display.

How to read the numeric display:

There’s a whole lot to say here, but let’s keep it simple:

  • -50dBm: perfect reception
  • anything greater than -100dBm: decent reception
  • anything less than -110dBm: you pretty much have an expensive iPod Touch

For more info, check out this wikipedia page