This blog post is more of a bookmark for me. Also, this will help you to unlock your AT&T Lumia devices without inserting SIM. I am not sure about other AT&T handsets, but it works on Lumia devices smoothly without any issues.
It’s not as easy to get a micro SIM or a mini SIM in all over the world and thus unlocking a device is quite difficult. This small post will help you to unlock the device in case you don’t have the SIM.
Recently, I got an AT&T handset which I had to unlock using the unlock code but the problem raised when I had to insert the SIM. The Lumia device for which I wanted to unlock it requires a mini SIM, which I don’t have. I doubt, it is available in my city too!!!
So, how to unlock the device? Finally, found the way to unlock the device without inserting the SIM. Though the step was very easy in first look, but it was not that much easy. I will say the reason later point of the post.
Here is the steps which you need to follow:
- Switch ON your phone without SIM Card
- Compose #PW+CODE+1# in the dial pad 
- Click the OK button to confirm the unlock code
That’s it. You will now have a confirmation that will unlock your Lumia handset for AT&T without actually entering the SIM card in the device. I assume that, this is the same process for the other AT&T models too.
To get letter P press * button quickly 3 times
To get letter W press * button quickly 4 times
To get letter + press * button quickly 2 times
The tricky part is here. By pressing * button for no. of times mentioned above will not actually show you the actual character in the dial screen, but actually show the * in that screen for ‘n’ nos. of time you pressed it. Regardless of what is actually visible in the screen, it actually handle the code internally.
I hope, this post will help you to unblock the AT&T handset without inserting the SIM. If you have SIM already, you don’t have to follow the above steps. Just insert the SIM and restart the device. It will ask you to enter the unlock code directly.