iOS 4.1 Brings Field Test Mode Back To The iPhone

iOS 4.1

Folks at Gizmodo have discovered that iOS 4.1 brings the Field Test mode back to the iPhone, which went missing in iOS 4.

Apple had released iOS 4.1 for iPhone yesterday. It includes fix for the proximity sensor, Bluetooth and iPhone 3G performance problems and some major features such as HDR photos, HD video upload, ability to buy TV show rentals and Game Center, Apple’s social gaming network.

The Field Test mode shows the antenna signal strength or more accurately signal to noise ratio in dBm rather than as bars.

To enter the Field Test mode, all you need to do is dial:


The signal bars will now display the signal in a dB reading as seen below.

iPhone - Field Test Mode

To exit “Field Test” mode, hit the Home button.

Signal strength ranges from roughly -50 to -105 , closer to zero means a better signal, i.e. – 50 (roughly full signal) is better than -105 (roughly no signal).

So if you plan to try it out, please let us know your results in the comment section below.

[via Gizmodo]

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  • saleh

    -55, doesnt go higher wen holding it in " death grip " 😀

  • DL

    Interesting that if you tuch the numbers with your finger they change to bars and vice versa. Why didnt apple make functions like that? Turning on off wifi like that…
    And so on..

  • BigRob

    No luck "error proforming request. Unknowen error"

  • Kurt

    Fascinating! I know what I will be playing with for a while. 3 bars = -88, with hands around bottom of phone it goes to 2 bars = -103. iphone 3G.

  • -kc

    without deathgrip = -87
    with deathgrip = -95

    downtown SJ, CA (16th floor)

  • Q

    number didn't work

  • Not working with me. 🙁 🙁

  • keymastur

    try upgrading to 4.1 first…

  • got to be on 41 ?

  • lolumadbro

    Yeah man reading is hard.

  • Golf4283

    Won't work for me either. Wonder if it's cause I didn't upgrade the baseband.

  • go kill ur self smartass!!!!!!!!!!!!!!!

  • lolumadbro u must be mexican go home and hill ur self

  • slamr

    -109 great ATT service as always from my home! I don't even have enough service to call and complain or use Mark the Spot App LOL.

  • Michael

    Works for me. You don't have to upgrade the baseband to use this.

  • Z

    lol umad?

  • Z

    dude you ARE mad, his username fits perfectly here

  • -110 with deathgrip

    -80 without deathgrip

  • yonbala

    iphone 3g 3.1.2
    no grip -87
    regular grip -98
    death grip -105
    all shows full bar

  • Alan

    84 to 92 fido. Not that good. Could be slot better

  • Duh

    IT WORKS ON 4.0.1

  • moronFighter

    @who cares: lmfao, what's wrong with you?

  • Z

    who cares

  • nobdy ???????????

  • l8te9ight

    Same here slamr, its a shame when you have to call at&t from a landline just so you can complain! Im sure they use the transcripts from some of my calls as training. lol

  • keymastur

    that's for a JB phone…these instructions are for a non-JB 4.1

  • Charlie

    -83 Financial District, NYC

  • I know I might have been an ass saying what I said… but Instead of bitching Im here to offer all of you in the blog some info… If the dev team would want to make a permenent solution to the jailbreak it is posible… they would only have to program the exploit they found on the bootrom… seeing how apple could only fix that problem after that on a Iphone 5 (a new phone) as for what I said about a program being written in 15 minutes, for any linux user a program to jailbreak a iphone would be mad In C or Perl in minutes and yes it would work right off the bat but I forgot that these fixes are made so that its easy for everyone so I will say they do need some time (not to much) and as for the dev team being on apple pay role… why not… Unlocking the phone would make it sell millions more… probably did this to supply the demand in the US first.

  • I couldn't make it work here in Germany. 🙁

  • dev_team

    move to another country

  • BlurKing

    Tip: Force quit the field test app and you get to keep the numeric signal strength thing.

  • Baka

    -62 -65

    Telstra NextG

    -72 -92


    I'm not sure how, but on my iPhone 4g I had this all the time for both signal and wi-fi and also battery strength. I could revert to icon just by touching whichever I wanted to change. Since downloading 4.1 this has been lost. I presume it was something in my i-tunes back which had stayed from a previous jail-break.