How strong is your iPhone signal? No Jailbreak required

Have you ever wondered how strong your mobile signal really is, and facepalmed at not being able to make a call even when it shows you have at least one bar? Well, theres an app for that, sort of...

Thanks to a cool tip over at Redmond Pie, iPhone users can change the signal bars to numbers that show just how strong (or weak) your iPhone signal really is.

It can be handy if you're in a so called "dead zone" where it's difficult to get any signal at all, viewing the numbers can make the difference on where you stand to make that call that needs to be done. The signal is measured in decibels, the lower the number is, the stronger the signal.

Before and after, wait what!

Jailbreaking isn't required, and the process is totally reversible, as I've discovered myself on a stock iPhone 4. We aren't sure on which particular models this tweak works, so just give it a try.

Follow the steps below:

  1. Dial *3001#12345#* on your iPhone then press Call.
  2. You’ll now enter Field Test mode. You’ll notice a signal strength indicator on the upper left hand corner of your screen. You can toggle between signal strength bars and a number by simply taping on it. At this point, press the home button to exit the app or if you would like the feature to be permanent, continue on. Don’t worry, the process is completely reversible.
  3. Hold down on the Power button until you see the ‘slide to power off’ bar.  Do not power off the device.
  4. Press down on the Home button until the app closes and you return to your home screen.

That’s it. Even when restarting the iPhone, the signal strength can be toggled between bars and numbers. The closer your number is to zero, the stronger your signal is.

To return to the default bars permanently, follow these steps:

  1. Dial *3001#12345#* on your iPhone then press Call.
  2. Press on your Home Button once.

As it turns out, the signal in my office sucks. Post your results below.

Source: Redmond Pie

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48 Comments

Commenting is disabled on this article.

A 3dB drop is already half the signal strength. That's why there's always some algorithm to come up with the bars. People dont have that in mind and often thinks this is linear. But a -96dBm is 4 times better than a -102dBm. So the usefulness of this is rather ... limited.

Julius Caro said,
A 3dB drop is already half the signal strength. That's why there's always some algorithm to come up with the bars. People dont have that in mind and often thinks this is linear. But a -96dBm is 4 times better than a -102dBm. So the usefulness of this is rather ... limited.

You are correct in that it isn't linear, but dB is not the same thing as dBm...

O.k. Let's say you know exactly the strength of the signal! What would that help in?
Add a couple of d digits to it to be more precise!

You didn't read everything... it's right there towards the end of step 2..
"... or if you would like the feature to be permanent, continue on. Don't worry, the process is completely reversible.
3. Hold down on the Power button until you see the ‘slide to power off' bar. Do not power off the device.
4. Press down on the Home button until the app closes and you return to your home screen."

S_Herbie said,
Isn't it digital?
You either have a signal or you don't!

No...haha. Are you being funny? Can't tell if serious.

Anyway, no. It may be 'digital' in the way the information is exchanged, but the signal is still an analog one and the signal strength matters.

T1Famous said,
I keep getting Unknown command

Did you type the last *? I forgot that one too and it gave me the same error.

The best signal strength would be between -45dBm and 85dBm.
-45dBm means very good signal strength but below it (-1 to -44) is considered harmfully.
Above -85dBm (meaning -90 and more) you may be able to perform calls but quality and internet speed will degrade.

SuperKid said,
So what's a good number??? Mine says -108 and goes to -114 xD

Well, mine came up as -81, and that's the full five signal bars in normal mode, so your is probably near-perfect.

MightyJordan said,

Well, mine came up as -81, and that's the full five signal bars in normal mode, so your is probably near-perfect.

Lower number means better signal

MightyJordan said,

Well, mine came up as -81, and that's the full five signal bars in normal mode, so your is probably near-perfect.

Well actually I am on 1 bar here so that must be quite low haha, never get any good signal when im indoors at home.

Neobond said,
Lower number means better signal

But -108 is lower than -81, isn't it?

EDIT: Found clarification on another article...

A signal of -60dBm is nearly perfect, and -112dBm is call-dropping bad. If you're above about -87 dBm, Android will report a full 4 bars of signal

So the article should actually state "the HIGHER the number is, the stronger the signal" (as it's working in negative numbers).

Neobond said,
What? -112 is call dropping -60 is near perfect. 60 is lower than 112 and it's numbers we're talking here lol. Ignore the -

Yes, 60 is lower than 112, but it says -60 and -112, which are negative numbers, so technically, -112 is lower. This is 11-14 year old maths we're talking about here!

And apparently, you're not supposed to ignore the minus sign, as the dBm scale works in both positive and negative numbers: http://en.wikipedia.org/wiki/DBm

Neobond said,
What? -112 is call dropping -60 is near perfect. 60 is lower than 112 and it's numbers we're talking here lol. Ignore the -

You didn't do well in math did you? Just kidding.

A minus sign is part of a number's value, ignoring it changes the value. You're just suggesting using the absolute value I suppose.

Wouldn't it have just been easier if the author had said "The more negative the value, the weaker the signal." ?

bitslasher said,

You didn't do well in math did you? Just kidding.

A minus sign is part of a number's value, ignoring it changes the value. You're just suggesting using the absolute value I suppose.

Wouldn't it have just been easier if the author had said "The more negative the value, the weaker the signal." ?

the HIGHER the number, the better. -60 is higher than -112.


testman said,
And if you're on Android, this info (and more) can be found by tapping Menu, Settings, About Phone, Network.

This doesnt change the bars to numbers at the top though (like this article shows how to do for iPhone)

Intrinsica said,
It's like you read my mind!

Now if only there were a way to display that instead of the reception bars...

it's still sort of pointless. nobody thinks in dBs.