Friday, December 3, 2010

iPhone 4 OS 4.2.1 Field Test Mode

If your iPhone is still in lower OS version, you should upgrade the firmware to IOS 4.2.1 now to enjoy the field test mode again.

In IOS 4.0 no Field Test Mode was given.  In IOS 4.1, only the signal bar changed to signal level without any detail information. Now ISO 4.2.1 give all the detail as before with the signal level indicator.

The latest version (Nov 2010) is 4.2.1 (8C148). Some screenshots are attached.

p.s. to activate field test mode of iPhone, type *3001#12345#* and hit call


Gianluca March 5, 2011 at 5:05 AM  

hi do you know if there is a program similar to celltrack for iphone 4?

Anonymous September 13, 2011 at 9:03 AM  

How do you tell what site and sector you are on

fab October 14, 2011 at 12:52 PM  

Still running on iOS 5

Anonymous November 26, 2011 at 11:59 AM  

how can I use it in dedicated mode?

Anonymous December 1, 2011 at 1:53 AM  

place a call and than add a call like confrance call and type code digits. don't forget pressing "call" at the end

Caroline Smith February 27, 2015 at 1:58 AM  

Versions of iPhone change, but actually nothing changes :) I work with iphone app development and iphone apps are practically the same inspite of the fact that they released iPhone 6 and iOS 8.

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