Secret codes reveal information on your iOS or Android phone
Instead of the dots signifying signal strength in the upper left of the screen, you will see a number representing decibels. A reading in the range of -40 to -80 is very good. Any reading of -110 and lower would represent a very poor signal. To return to the dots, use the code again to open the Field Test screen and close it with a single tap on the home button. Other codes include the *#06# that will show your phone's unique IMEI number, and *#33# will show you if your iPhone is enabled for voice, SMS and data.
Android codes are harder to list since many are manufacturer-specific. We can pass along a couple that should work on all Android devices. To view multiple screens of information pertaining to battery usage, Wi-Fi configuration and more, punch in *#*#4636#*#* on the dialer. Dial *#*#1472365#*#* to see information about Google Calendars.