Android phone has lot of interesting features for you to uncover, but to get the features you need to perform certain actions or access a particular menu on your phone. Here is how you can diagnose Wi-Fi problems, factory reset and see usage statistics of your Android phone by simply dialing certain codes.
If you are having problems with your Wi-Fi, type the code *#*#526#*#* on the dial pad, it will scan and diagnose any problems with the WLAN connection.
If you want to factory reset your phone, just dial this *#*#7780#*#* code. It will remove everything stored on your device, but nothing that is stored on your external SD card.
Want to get battery information, usage statistics and battery history, dial the code *#*#4636#*#* and this will activates a screen that displays the information mentioned above.
There are several such secret codes for your Android phone. To get full list of code, head over to this page.