b758e25a_s___Smartphone_Review_and_Tips__Function
[Code] *#*#4636#*#* [Description] Displays the hidden testing menu for android which provides details on application usage, battery health and status, Wifi information and general network information. If you suspect that you battery is giving problems this is the best place to check. You can also force certain network choices here, for example if you wanted to force your Android t use only 3G or GSM you could do it from the Phone Info menu [Function] 
Testing Mode – Phone Setting
I M E I
T e s t i n g M o d e – P h o n e S e t t i n g
F i e l d T e s t
P U K u n l o c k
D i a l e r L o g E n a b l e d
D i a l e r L o g D i s a b l e d
Android secret codes | Smartphone Review and Tips
Function