i Phone Secret Codes

1) *3001#12345#* and tap Call. Enter Field Mode.Field mode reveals many
   of the inner settings of your iPhone,
   specifically up-to-date network and cell information.
   2) *#06# Displays your IMEI. No need to tap Call.IMEI is the unique
   identifier for your cell phone hardware.
   Together with your SIM information it identifies you to the provider
   network.
   3) *777# and tap Call. Account balance for prepaid iPhone.
   4) *225# and tap Call. Bill Balance. (Postpaid only)
   5) *646# and tap Call. Check minutes. (Postpaid only)These three are
   pretty self explanatory.
   6) *#21# and tap Call. Setting interrogation for 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.
   7) *#30# and tap Call. Calling line presentation check.This displays whether
   you have enabled or disabled the presentation of the calling line,
   presumably the number of the party placing the call.
   Cool *#76# and tap Call. Check whether the connected line presentation is
   enabled or not.State whether the connected line presentation is enabled
   or disabled. Presumably similar to the calling line presentation.
   9) *#43# and tap Call. Determine if call waiting is enabled.Displays call
   waiting status for voice, data, fax, sms,sync data, async data, packet access
   and pad access. Each item is either enabled or disabled.
   10) *#61# and 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.
   11) *#62# and 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.
   12) *#67# and tap Call. Check the number for call forwarding when the iPhone is
   busy.And again, but for when the iPhone is busy.
   13) *#33# and tap Call. Check for call control bars.Check all the usual suspects
   (voice, data, fax, sms, etc) to see whether barring is enabled or disabled for
   outgoing.