Q: how to know if my iphone has been unlock?

The last part of the instructions says to do a restore, and you should receive a "Congratulations" message. If you do not see that, it may not be unlocked. The only other way to test is to put a non-AT&T SIM in the phone and see if it works.

Try using a different sim card from a different phone carrier.

According to the two AT&T reps I spoke to after receiving an email from them saying my phone had been unlocked, you will not receive a "congratulations" screen notification.  If you have any doubts as to whether it has been unlocked, insert a non-AT&T sim card, or check it on one of the following websites.

http://s-url.ro/

http://iphoneimei.info/

http://iphoneox.com/

I just unlocked my AT&T iPhone 4.  I went through the process by:

1. doing an online chat with AT&T wireless technical support

2. giving them the IMEI number for the AT&T iPhone 4

The technician then gave me the following directions:

___

1. Open iTunes on your Mac or PC and verify that you have internet connectivity.

2. Connect your iPhone using the dock connector to USB cable that came with your iPhone.

3. Backup and restore your iPhone using iTunes. For information on backup and restore, please visit http://support.apple.com/kb/HT1414.

4. After restoring, your iPhone will be unlocked.

5. Make sure that you are using the latest version of iTunes and that you have an active or inactive sim card in the phone while restoring.

Additional information on unlocking can be found at http://support.apple.com/kb/TS3198. For questions regarding AT&T’s wireless service and iPhone, please visit the Phone/Device Learning Center.

_____

In step 3, make sure you do a full backup and then the key is to use the "Restore iPhone..." button.  This redownloads the entire currently supported iOS for the device, erases the iPhone, you then see a message in iTunes congratulating you that the iPhone was unlocked, and then you can restore the iPhone from backup.

@seanachai51: I used the iphoneimei link you posted and got my confirmation. Thanks!

You're welcome.

The reason for getting your iPhone unlocked is to enable you to to use another carrier's SIM and account.  If it worked should be self evident.

@tonefox: in the US, iPhone users are stuck in long contracts with their carriers, of which there are only a few to choose from. When we travel overseas we either need to arrange to unlock our phone before we go (which our carrier will only allow us to do after our contract has expired), or buy a cheap cell phone in our destination country. The vast majority of people don't have unlocked phones; getting someone else's sim card and sticking it in our phone to confirm would be way more of a hassle than going to the website that seanachai51 posted. Therefore, a well earned thanks to seanachai51 for reducing the overall hassle level was warranted.

I went to the imei sight and enterd my number but what implies that it is unlocked ?? Because I didn't see anything that said "locked" or "unlocked" plz help

Of late you will get a message 'Server Down' regarding lock/unlock status on these sites.

Only AppleCare can tell you for sure if your iPhone is unlocked.

Other way is as stated by tonefox above

There is a notification. 

I am an AT&T user.  After calling them and putting in the request, I was told to connect to itune, backup and restore the iphone to get it unlocked did not work the first time and here is the trick....

Make sure you have a SIM card in the phone.  Does not matter if it is an active or dead one.

Backup with Entryption on.

Now this are the trick parts.... after backup, go to iPhone and earse all content.  (Setting / General / Reset / Erase All Content)

Use the new phone setup assistance to restore from iTune. 

1.Ensure your iTune is already open.

  2.Follow the steps on the iPhone, when it comes to asking for a Wifi connection, skip

  3.Pick Connect to iTune to restore

  4.Plug in you iPhone, wait a little while for iTune to pickup your iPhone, then pick restore from you last backup

The notification of your iPhone is now unlocked will be the first thing displayed on your iTune.... not your phone.

Oh, http://iphoneimei.info/ also show the status correctly.....

I'm unlocking an old iPhone in preparation for a trip to India.  I won't have another SIM card until I arrive in India, so can't test it until then.  I'd like some confidence that it's unlocked as I won't be taking the iMac with me.

Just put another networks sim card in the iphone other than the network you were original using. It will be self evident whether it has been unlocked or not as it will recognise the sim card and you will be able to use your iphone as normal

You will see in the bottom part of the status message as

SIM LOCK:::: Unlocked;

that shows your iPhone is unlocked !!