Do you mean unlock it to use it by sliding across and entering your passcode if you have one set?
Do you mean you have forgotten this passcode?
Or do you mean unlock it from a carrier?
If the latter you have to process the unlock through whatever carrier it is locked to. If it is AT&T you have no official way to unlock it, they won't do it.
Call your carrier and ask.
Depending on where you are it may be offered for a fee. Also call AppleCare and harrass them a little, they usually say it's strictly up to the carrier. When you call the carrer they like to say it's Apples fault for not giving them the codes! It's a fun game, but at the end of the day if the Carrier doesn't offer unlocking you may need to search the classifieds instead.
Telus, a Canadian company, refuses to unlock phones even after the device balance is paid in full. Some companies will allow you to unlock regardless of paying out the balance, as you're generally still bound by contract for data plans and such.
I sort of agree. If you do not mean carrier lock and do not mind losing all the data, I believe you can reset the phone to factory settings with iTunes. From what I heard the normal factory update will keep the settings but if you do a full restore (e.g. DFU mode) it will be like a new phone.
If you are looking for carrier unlock you can try writing Mr. Tim Cook like the example in the following article:
If your contract is up I believe it should be unlocked (in the USA), it seems unAmerican and anti-competitive, but if your in the USA there are really no other 3G carriers that support GSM iPhones.
You have 2 problems. The first is that you are not entering the proper unlock code. The second is that you have voiceover turned on in Accessibility settings. If you can't remember the unlock code you must restore the phone using iTunes on the last computer you synced it with. This will remove the passcode.
AT&T will unlock your iPhone if you meet their requirements. It is on their website. Just search unlock iphone. You have to be current and finished with your contract obligation. They have a form you fill out to request the unlock. Here is their response after I requested my iPhone 4s be unlocked.
Thank you for contacting AT&T Customer Care about unlocking your iPhone.
We have reviewed your request and confirmed that you are eligible to have the requested iPhone unlocked.
Please allow 24 hours upon receipt of this notification to complete the unlock.
To complete the unlock, simply:
- Open iTunes on your Mac or PC and verify that you have Internet connectivity.
- Ensure a SIM card is inserted into your iPhone.
- Connect your iPhone using the dock connector to USB cable that came with your iPhone.
- Backup and restore your iPhone using iTunes. For information on backup and restore, please visit http://support.apple.com/kb/HT1414.
- After restoring, your iPhone will be unlocked.
Additional information on unlocking can be found at http://support.apple.com/kb/TS3198
You may also check the status of your unlock request by clicking the link for AT&T's Device Unlock Status Portal.
For questions regarding AT&T's wireless service and iPhone, please visit the Phone/Device Learning Center.
We thank you for your continued business.
AT&T Customer Care Team