*3001#12345#* tap Call. Enter Field Mode. Field mode contains lots of iPhone inner settings, especially newest network and cell information.
*#06# Shows your IMEI. No need to tap Call. IMEI is the unique identifier for your mobile phone hardware. *777# tap Call. Account balance for prepaid iPhone only.
*225# tap Call. Bill Balance. (Postpaid only) *646# tap Call. Check minutes (Postpaid only).
*#21# tap Call. Set interrogationfor call forwards. Discover the settings for your call forwarding. You’ll see whether you have voice, data, fax, SMS, sync, async, packet access, and pad access call forwarding enabled or disabled.
*#30# tap Call. Check the calling line presentation. This shows whether you have enabled or disabled the presentation of the calling line, presumably the number of the party placing the call.
*#76# tap Call. Check whether the connected line presentation isenabled or not. State whether the connected line presentation is enabled or disabled. Similar to thecalling line presentation.
*#43# tap Call. Determine if call waiting is enabled. Shows call waiting status for voice, data, fax,SMS, sync data, async data, packetaccess and pad access. Each item is either enabled or disabled.
*#61# tap Call. Check the number for unanswered calls. Show the number for voice call forwarding when a call is unanswered. Also show the options for data, fax, SMS, sync, async, packet access and pad access.
*#62# tap Call. Check the number for call forwarding if no service is available. Just like the previous, except for no-service rather than no-answer situations.
*#67# tap Call. Check the number for call forwarding whenthe iPhone is busy. And again, butfor when the iPhone is busy.
*#33# tap Call. Check for call control bars. Check all the usual suspects (voice, data, fax,SMS, etc)to see whether barring is enabledor disabled for outgoing.
Change screen brightness the screen brightens uses more battery power.
Change this underSettings -> Brightness
Turn off 3G If you are in a location
Turn off Wi-Fi
Turn off Bluetooth
Turn off push e-mail
Turn off GPS