Since the previous days of the cellular technology , the secret codes have been embedded into the software of our mobile phones, and the hidden features also. They are still in place today. Including the hidden codes in the iPhone is a special diagnostics mode you that can be used to troubleshoot problems, get a more accurate signal reception measurement, and more.
The diagnostics mode is known as Field Test, and you can enter it by opening up your iPhone’s Phone app and calling *3001#12345#*. You’ll be met with a list of technical measurements and menus that are really only of interest if you’re professionally testing network infrastructure or phone hardware.
Of most interest to casual users is a choice to show a more accurate reading of the signal strength. In Field Test mode, press and hold the Power button until as usually you see the slider, then pressing on hold the Home button until the home screen shows-note instead of dots. The note is that you now have a numerical reading.
Anything between -40 and -80 is very good. Anything below -110 and then you will be on pretty shaky ground
Or network-wise. To move backward to the normal dots, jump back into Field Test mode and then exit it as you usually did with a single press of the Home button.
It’s a most useful feature to have while you’re testing mobile signal in your house or you’re out and want to know if your next call is going to last without dropping. It is an old trick that’s been around a fair while it’s always worth highlighting the hidden options as there will be people not yet aware of them.
There are also other hidden codes, but they’re not quite as useful and be apt to vary based on your carrier and your country, so they’re not as reliable either. *#06#displays your iPhone’s unique IMSEI (International Mobile Station Equipment Identity) number.
For example, *#33# is a code that checks whether voice, SMS, and data are enabled or not.
There are several such codes for android devices too,but they have the propensity to be manufacturer-specific, so putting together the present master list is more tricky. Try *#*#4636#*#* to bring up several screens of information on your phone, battery usage, and WiFi configuration or *#*#1472365#*#* to see information about your Google Calendars and hidden features.