The trick that makes iPhone use a bar-line number

Under Apple's default settings, the iPhone will indicate the strength / weakness of the phone wave with 5 dots at the top left corner of the device. However, if you do not like it, you can apply the procedure below to make iPhone replace 5 dots with negative numeric values.

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Step 1 : From the screen press the call key, press * 3001 # 12345 # * and press the call button

Step 2 : After pressing the call button, you will be able to access the Field Test mode and you will see a negative number appear instead of the 5 dots at the top left. The closer this negative number is, the stronger the wave

Step 3 : If you press the Home button to exit Field Test mode, the dot row will reappear. In case you want to continue using negative numbers, do the following: Press and hold the Power button until the " Slide to power off " message appears. Next, release your hand on the power button and press and hold the Home button for about 5 seconds until you exit the Field Test mode. Negative numbers represent the strength of the wave that will be retained, and you can toggle between numbers and dots by touching them with your fingertips.

Step 4 : To completely exit the negative numbers and return to Apple's default settings, open the Field Test again as in step 1 and press the Home button to exit this mode instead of holding down the power button as instructed above.

Good luck!