Secret USSD Codes for the iPhone 

So what is USSD exactly?Unstructured Supplementary Service Data (USSD) is a technology that allows users to access various services through the use of short codes. It usually consists of a number that start with a * and end with a #.

All of these USSD codes need to be entered via the Phone app, and require the input of a handful of digits and characters followed by a tap on the call button. It’s not difficult, but do be careful; sometimes, messing around with these things can cause some serious problems down the line. You’ve been warned.

Now, with that out of the way, here are the codes you’re going to need!

*3001#12345#* – Activate Field Mode, which contains all of your iPhone’s more technical settings. It also converts the signal bars into an actual number.

*#5005*7672# – Check SMS center

*646# (Postpaid only) – Display your available minutes

*225# (Postpaid only) – Check your current bill’s balance

*#31# – Choose whether to hide your number

*3370# – Enable or disable EFR (Enhanced Full Rate), which improves your iPhone’s voice quality, but will quite likely reduce battery life

*#21# – Check call forwarding status

*777# (Prepaid only) – To check the account balance

*#62# – Check which number calls will be forwarded to if no service is available

*#76# – Check connecting line presentation

*#67# – Check the number to be used for call forwarding

*#33# – Check whether anything is barred, such as international calling etc.

*#61# – Check number of missed calls

*#06# – Displays your iPhone’s IMEI number

*#43# – Check call waiting status

*43# – Activate waiting

#43# – Deactivate call waiting