I did not try any of these, but the are supposed to work on the iPhone (some maybe AT&T specific), use at your own risks:
| Code | Comment |
|---|---|
| *#0*# | various diag |
| *#06# | This displays the International Mobile Equipment Identity (IMEI) - the unique ID code for each phone. |
| *#21# Call | This displays various Call Forwarding settings. |
| *#30# Call | This displays whether or not your iPhone will display caller ID or numbers for incoming calls. |
| *#33# Call | This displays whether Call Blocking is enabled for outgoing calls. |
| *#43# Call | This displays the status of Call Waiting. |
| *#61# Call | This displays the total number of calls forwarded to voicemail when the phone was unanswered. |
| *#62# Call | This displays the total number of calls forwarded to voicemail when the phone was powered off or outside the service area. |
| *#67# Call | This displays the total number of calls forwarded to voicemail when the phone was busy. |
| *225# Call | This displays the current monthly balance. |
| *646# Call | This displays the remaining monthly minutes. |
| *777# Call | This displays the pre-paid account balance. |
| *#3001#12345 Call | This activates Field Test Mode, which reveals tons of hidden settings and data for the iPhone and network. These values should not be changed unless you know exactly what you’re doing. |