Apple introduced a massive redesign to its smartphone operating system with iOS 14 that broke cover during WWDC 2020. Apart from widgets on the home screen, App Library, compact calls UI, and the Picture-in-Picture mode for iPhones, the company has also redesigned the Field Test Mode.
The Cupertino-based tech giant seems to have overhauled the Field Test Mode user interface. The new UI displays more information in one glance and has a new Home section where information about LTE Cell Servicing Info, Device Info, and breakdown of GSM, UMTS, and LTE functionality is displayed on the phone.
All the information that’s displayed in iOS 14’s Field Test Mode is also visible in iOS 13’s Field Test Mode, which means that this is more of a design overhaul rather than an exercise of adding more functionality or features. The Field Test Mode is designed for cellular operators and engineers so that they can know if something is wrong with an iPhone.
You can access the Field Test Mode on your iPhone by keying in *3001#12345#* on the Phone app’s keypad and dialing the number. Instead of calling the number, it opens up the Field Test Mode, and you can view the information that you need to glance upon.
The Field Test Mode can be used to measure cellular signal strength on your iPhone. After entering the mode, you can tap on ‘Servicing Cell Maes,’ which shows two numbers: rsrp0 and rsrp1. The numbers (ranging from -50 to -130) denoted by them are always negative, and the lower the negative number, the better signal your phone is receiving.[Source: MacRumors]