Need Network Unlock Code New SiM Card

https://www.att.com/deviceunlock/

    AT&T can only provide an unlock code for a phone that is locked to AT&T.  AT&T does not have unlock codes 4 phones that are locked to different service providers.  

If your phone is not an AT&T branded S7 Edge, it cannot work on at&t anymore as it's not VoLTE capable.

I should add I do not believe a PUK code will work.

Thanks very much for the response. You said it cannot work on at&t anymore as it's not VoLTE capable. Are you saying a change at at&t excluded non-Volte capable phones? if that made sense. Do you know if that change happened when at&t stopped supporting 3g? which was pretty recent I think??

My phone is 4g but has this big ol' Verizon brand on the back.

@karmajoe I won't pretend to be an expert on any here. My experience comes from trying to get unlocked international devices purchased from third party vendors to work on various networks.. for the better part of three years. 

According to the information that I found on your phone... it's VoLTE capable. That information comes from a website that I use to find information on the specs of a phone before I buy it. 

However, it appears that your phone... while also, according to you, being branded by another carrier (which is one of the things that gets a phone restricted)... doesn't have the HD Voice feature... which At&t claims is necessary for compatibility with the network. 

Some of the other variants of the Samsung Galaxy S7 Edge have the HD Voice feature built in. 

Although those are key factors for compatibility with At&t network... other things, such as: matching primary frequency bands for 4G; operating system updates (which version of Android a device is on... not including flashing a phone) could also cause the phone to be restricted. 

At&t also has a whitelist... or a list of devices that they claim are the only ones guaranteed to work with the network. The lists have exact make and model numbers of phones... and must be matched exactly for guaranteed compatibility... according to At&t. 

Some people in this forum have found different ways to get a phone to work with the network... including software updates, or flashing the phone (which I don't have any experience with). 

A method of workaround that was successful for me was seemingly removed in the post from this forum... when I attempted to explain it to others. 

As others here may tell you... the easiest way to ensure that your phone will have service with At&t is to buy one that's on the whitelist. 

Hope this helps. 

@karmajoe 

Hello karmajoe, we're here to explain why your device will not connect to the AT&T network.

If you have a 3G device, please note, it will no longer work on the AT&T Network. If you have a 4G device, it may not be compatible and not work depending on where it was purchased and the model #. For example, the Galaxy S20 models G981U and G981U1 will work on the AT&T network, but the Galaxy S20 models G981F, G981N, and G981O will NOT work. You'll find a full list of compatible devices. This is because they have different hardware that is not compatible with AT&T’s network (HD Voice, VoLTE compatible). 

If you purchased an unlocked device from another retailer, please note, they are not optimized to work on AT&T’s network. This is important to remember when purchasing a non-branded, unlocked device and why you see different model numbers.  

Find the model number on your device

First, make sure your device is compatible with AT&T’s Network. If it is not on the list, it may not work on our network. In instances like this, you’ll need to get a compatible device. 

If your device is compatible but is not connecting, the following may resolve the issues:

• Program the data settings for your non-AT&T device
• Get a 4G SIM for your 4G device or a 5G SIM for your 5G device
• Download the latest software – If you are an AT&T Customer, software downloads are automatic. If you have a non-branded device, you will need to go directly to the manufacturer.
• Make sure 4G is enabled on your device. Some customers disable 4G.
• Try a couple of solutions written by some community members
  • Solution 1
  • Solution 2

Please reach back out if you have any further questions or concerns.

Thank you for visiting AT&T Community Forums!

Carlton, AT&T Community Specialist