https://www.macrumors.com/2010/09/08/ios-4-1-restores-field-test-mode/
iOS 4.1 Restores Field Test Mode - MacRumors
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...
ios 4 1field test moderestoresmacrumors