*#43#
Use to verify if call waiting is enabled
*#61#
Verify the number for unanswered calls
*#62#
Verify the number for call forwarding if no service is available.
*#67#
Verify the number for call forwarding if phone is busy
*#33#
To verify whether barring is enabled or disabled for outgoing
*#21#
To display the settings for your call forwarding
*3001#12345#*
Enters Field mode which allows you to access most of the hidden settings and functions of your iPhone.
*#06#
Display the IMEI of your iPhone, as always this is the standard code for all brands of phones.
*225#
Displays the account balance for postpaid contracts.
*777#
Displays the account balance for prepaid accounts.
*646#
Displays the remaining minutes available.
*3282#
Get your data usage information.
*729
Options to make payments. Its operator specific.
