How to Test iPhone 4/3Gs/3G Antenna Reception on iOS 4.1 ?

What a big one! Gizmodo could find a way to check your iPhone 4's antenna reception issue which was discovered by iPhone 4 users when they hold the device from the bottom left. The method to test your antenna reception only works on the newly released iOS 4.1, check it below.

Follow These Steps :

•  you will have to upgrade your iPhone 4 (or any iPhone) to iOS 4.1 

(Note: It kills your jailbreak and unlock).

• Then, Dial *3001#12345#* into your phone.

Now, the signal bars will be replaced with a number (i.e. -89) as shown in the screenshot above.
The higher the number it is, the worse the signal it is.