Owners of iPhone smartphones can, using standard operating system tools, find out the exact signal level in the operator’s mobile network. Moreover, for this it is not necessary to expose the mobile device to a jailbreak procedure.

You can evaluate the quality of communication on the iPhone by counting the number of “circles” on the indicator in the status bar. A simple trick with the activation of the Field Test mode allows you to activate a special digital signal display mode on your iPhone. The numbers indicate decibels, that is, the amount of loss from the station of the cellular provider.

Thus, it will be possible to find a place with the best reception for making a call or sending a short message. Activation of this indicator is carried out using the service number.

Read more: Why is my iPhone Using so Much Cellular Data?

How to Find Out the Exact Signal Strength of a Cellular Network Field Test in iOS with iPhone Engineering Mode?

Instruction how to enter the iPhone Diagnostic mode you can find below:

  • Dial on the iPhone *3001#12345#* and press Call button;
  • The phone enters iPhone field testing mode.
How to Activate iPhone Cellular Field Test Mode?
  • A signal strength indicator will appear in the upper left corner of the screen. At this point, you can switch the display modes by touching the icon;
  • Now check for “Connected mode LTE Intra-frequency Measurment”;
How to Activate iPhone Cellular Field Test Mode?
  • Serving Filtered RSRP parameter is what we are looking for, this negative digit show the strength of the field;
How to Activate iPhone Cellular Field Test Mode?
  • Now you can press Home to exit or, if you decide to leave this mode, continue further;
  • That’s all, now diagnostic mode will remain even after the phone is rebooted. It can be switched with a simple tap on the icon.

To return the Standard mode, follow these steps:

  • Dial *3001#12345#* on the iPhone and make a call;
  • Click Home button to exit the Field Test mode or click Phone icon at the top.
How to Activate iPhone Cellular Field Test Mode?


Note that the in diagnostic mode signal value is always negative. The larger it is (that is, the closer it is to zero), the better the signal from the cellular network. For example, if the indicator is −80, then this means reliable signal reception, similar to the five points of the standard display. If the indicator is lower than −110, then the iPhone receives a signal of only one “normal” division.

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Hi there! My Name is Vincent Lago! My goal is to share insightful reviews, guides, and manuals for people looking to know more about current solutions for Apple hardware and OS. I have years of technological background knowledge including owning a custom iMacs & PCs which was using for different types of business. And now, I want to share my experience with you.

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