- Apr 12, 2001
Gizmodo reports that iOS 4.1 has reincluded the Field Test mode to iOS. Field Test mode allows you to get a numerical figure for your antenna strength rather than the traditional bar measure. To get to Field Mode:
Pressing Home will exit you from the Field Test mode. For reference, Anandtech provides a good discussion about bar strength. Since that article was published, Apple has remapped the signal strength to # of bar ratio. More negative numbers are worse, and Anandtech reports they were surprised they were able to hold calls with signals as low as -113db. First, upgrade your iPhone 4or any iPhoneto iOS 4.1.
Dial *3001#12345#* into your phone [and press Call].
Most customers won't care about their numerical signal strengths, but the antenna strength changes generated a lot of publicity surrounding the iPhone 4 launch due to issues with new antenna system.
Article Link: iOS 4.1 Restores Field Test Mode