This is Apple iphone Secret Codes

*3001#12345#* + tap Call. Enter Field Mode. Field mode contains lots of iPhone internal settings, especially newest network and cell information.
*#06# It shows your IMEI number. IMEI number is a unique identification number for your mobile phone hardware.
*777# + tap Call. It shows account balance for prepaid iPhone.
*225# + tap Call. It shows 'Bill Balance' for Postpaid only.
*646# + tap Call. Using this you can check remaining minutes (Postpaid only).
*#21# + tap Call. It is used to set interrogation for call forwards. It discover the settings for your call forwarding. Using this you can check whether you have voice, data, fax, SMS,sync, async, packet access, and pad access call forwarding enabled or disabled on your iPhone.
*#30# + tap Call. It is used for 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. It is used to check whether the connected line presentation is enabled or not.
*#43# + tap Call. It is used to check if call waiting is enabled for your iPhone or not. It also shows call waiting status for voice, data, fax, SMS, sync data, async data, packet access and pad access. Each item is either enabled or disabled.
*#61# + tap Call. Used to check the number for unanswered calls. It also show the number for voice call forwarding when a call is unanswered and also show the options for data, fax, SMS, sync, async, packet access and pad access.
*#62# + tap Call.  This code can be used to check the number for call forwarding if no service is available.
*#67# + tap Call. This code can be used to check the number for call forwarding when your iPhone is busy on another call.

Source : techsavyshweta