Like we all know, new iPhone 4 got many issues included Antenna Gate. There are an update on iOS 4.1 that we can use to check Apple iPhone’s Singnal Strength. To do this we can monitoring RSSI (Received signal strength indicator) bar on their devices and if you wonder how you can track its signal strength change more accurately without relying on its 5 level bars.
To do check Apple iPhone’s Signal Strength in iOS 4.1, we only need to call this number *3001#12345#* and hit call button. And your signal bar will be change like this one. To switch back you only need to hit quit button / big button on the bottom of your screen. My Digital Life said, this function only work on iPhone 3G/3GS/4 and must be on iOS 4.1, maybe on iOS 4.2 will be made more details and comprehensive field test measurements.