With included documentation as sparse as Apple's, there are plenty of them...
Really, really hidden features that will only appear if you chant the correct spells:
to bring up the spirit of iPhone's Field Test mode (this is different from the DFU mode familair to jailbreakers), which will give you information about towers and signal strength, 3G/EDGE network and much more info which no mortal would ever need.
will display your IMEI. No need to tap Call.
And some spells that only works in AT&T land:
*777# and tap Call. Account balance for prepaid iPhone.
*225# and tap Call. Bill Balance. (Postpaid only)
*646# and tap Call. Check minutes. (Postpaid only)
And a few more enchantments related to call forwarding :
*#21# and tap Call. Setting interrogation for call forwards.
Discover the settings for your call forwarding. You'll see whether you have voice, data, fax, sms, sync, async, packet access, and pad access call forwarding enabled or disabled.
And lots and lots of other spells for all occassions, phew...
*#30# and tap Call.
Calling line presentation check.
This displays whether you have enabled or disabled the presentation of the calling line, presumably the number of the party placing the call.
*#76# and tap Call.
Check whether the connected line presentation is enabled or not.
State whether the connected line presentation is enabled or disabled. Presumably similar to the calling line presentation.
*#43# and tap Call.
Determine if call waiting is enabled.
Displays 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# and tap Call.
Check the number for unanswered calls.
Show the number for voice call forwarding when a call is unanswered. Also show the options for data, fax, sms, sync, async, packet access and pad access.
*#62# and tap Call.
Check the number for call forwarding if no service is available.
Just like the previous, except for no-service rather than no-answer situations.
*#67# and tap Call.
Check the number for call forwarding when the iPhone is busy.
And again, but for when the iPhone is busy.
*#33# and tap Call.
Check for call control bars.
Check all the usual suspects (voice, data, fax, sms, etc) to see whether barring is enabled or disabled for outgoing.
originally submitted by GeneQ on Super User.
Scenario: You are trying to take a picture of yourself (and perhaps a friend), so you have the phone turned around, and you cant seem to hit the "shutter" button to take a picture.
Tip: Hold your finger on the "shutter" button, turn the phone around, and when you are ready to take a picture remove your finger. The picture will be taken when you remove your finger. This is much easier than the "old" approach.
Special characters on the keyboard.
- Hold down E, Y, U, I, O, A, S, L, Z, C, or N to bring up accented letters
- Hold down $ in the number/symbol keyboard to display other currency symbols
- Hold down “ or ‘ in the number/symbol keyboard to access alternative quote characters
- Hold down ? or ! in the number/symbol keyboard to bring up the ¿ or ¡ symbol
- Hold down the .com key when entering Web addresses to bring up options for .net, .edu and .org. (You can also do this trick when entering email addresses in Mail by tapping and holding the . (period) key.)
originally submitted by Herb Caudill on Super User.
Go to Settings->General->Keyboard, and turn on Enable Caps Lock. When typing the shift key will still behave as before, but now you will have the option to double-tap it to turn on Caps-Lock (shift key will turn blue). Useful for acronyms, and shouting.
originally submitted by jwaddell on Super User.
You can play videos even when the phone is locked.
Sometimes I listen to video podcasts, where all I am interested in is the audio. When doing this, if you lock the phone the podcast stops playing.
However, you can start the podcast playing again even with the phone locked. Just double press the home key to bring up the iPod controls and then press play.
originally submitted by andynormancx on Super User.
In 3.0, you can adjust the scrubbing speed through a song by touching the scrubbing slider, then moving your finger down on the screen. Different distances from the scrubbing bar mean different (slower) scrubbing speeds.
While it's not exactly private browsing, you can clear your Safari history, cookies, and cache from the Settings application in the Safari menu.
The Home button (when pressed in the Springboard) by default will send you to the first screen of applications. However, if you press Home, wait for the first page of apps to be displayed, then press Home again, the Search screen will be presented. Subsequent presses will toggle back and forth between the first apps page and the Search page. (Note that you have to delay slightly between presses, otherwise the two-press shortcut will kick in and launch some other app (iPod by default)).
originally submitted by Tim on Super User.
You can listen to any audio that is being streamed through Quicktime in Safari (.mp3, .m3u, .pls etc files) in the background.
Start the stream via a link in Safari.app, and then hit the home button and the audio will continue to play.
This was very notable pre-iOS4, not sure if it worked pre iOS3 though.
You can have more than the 11 screen limit for apps. If you add them, they won't be displayed, but will still be installed on the phone.
You can still get to them by using a spotlight search for the app name and launch them, even though they're not visible.
originally submitted by Mark Struzinski on Super User.