Apple iPhone secret codes:

Some usefull codes for your iPhone

*3001#12345#* and tap Call: Field Mode (iPhone network and cellular information)
*#06# : IMEI number.

*777# and tap Call: Pre-paid account balance.

*225# and tap Call: Post-paid account balance.

*646# and tap Call: Post-paid minute balance.

*#21# and tap Call: Call feature settings (enabled/disabled) for voice, data, fax, SMS, sync, async, packet access, call forwarding.

*#30# and tap Call: Caller-ID display check (enabled/disabled)

*#76# and tap Call: Connected call display check (enabled/disabled)

*#43# and tap Call: Determine if call waiting is enabled.

*#61# and tap Call: Call forwarding number with service (no-answer)

*#62# and tap Call: Call forwarding number without service (no-ring)

*#67# and tap Call: Call forwarding number when busy

*#33# and tap Call: Check outgoing services for call-barring (enabled/disabled)