here are some tricks and codes which can be useful if you have an android phone.
Cell Battery , WiFi Usage e.t.c Info:

*#*#4636#*#* Restore Factory Settings: *#*#7780#*#* Format Phone: *2767*3855# Launch service mode: *#*#197328640#*#* Test WiFi:

*#*#232339#*#* 0R *#*#526#*#* OR *#*#528#*#* Display WiFi MAC address: *#*#232338#*#* GPS test: *#*#1472365#*#* Other GPS test: *#*#1575#*#* Bluetooth test:

*#*#232331#*#* Display Bluetooth physic address: *#*#232337#*# Start Gtalk monitoring: *#*#8255#*#* PDA, Phone, H/W, RFCallDate: *#*#4986*2650468#*# * PDA and Phone: *#*#1234#*#* FTA SW version: *#*#1111#*#* FTA HW version:

*#*#2222#*#* PDA, Phone, csc: *#*#44336#*#* Packet Loopback: *#*#0283#*#* LCD test: *#*#0*#*#* Melody test: *#*#0673#*#* OR *#*#0289#*#* Device test such as vibration and lightness: *#*#0842#*#*

Display touchscreen version: *#*#2663#*#* Touchscreen test: *#*#2664#*#* Distance sensor test: *#*#0588#*#* Display memory version: *#*#3264#*#*