So ATT turned off my 4G LTE Galaxy A71

It does not have AT&T software version of VoLTE,  HD voice.   

So this was to be expected. 

Non carrier branded phones that will work on AT&T

@chucklilly I won't pretend to be an expert or anything here. 

Your phone has everything necessary to be compatible with AT&T network (depending on the exact variant of model Galaxy A71 you have as far as matching the primary frequency bands).

Because it's an international device, AT&T won't allow it to work. Their system is setup to flag and restrict access to the network of any IMEI number of a phone it deems incompatible. 

The phones on AT&T's whitelist are the only ones that At&t guarantees to work. 

However there are workarounds for keeping your device (again assuming you have a variant of the Galaxy A71 matching AT&T's primary frequency bands).. one of which involves changing the IMEI the system sees to a number from a phone that At&t claims is compatible. 

I'm currently using that workaround for a Galaxy A70 on a prepaid account setup after February 22. 

If the phone has been flagged the work around won't work.  I tried this on a older a50 the other day just for giggles as it was flagged on a friends account.

@GLIMMERMAN76 I appreciate your response 

I think it's awesome that people are attempting to find workarounds for their phones. 

And the more found the better. 

The one that I'm currently using on my Samsung Galaxy A70.. is still working. 

I'm using the phone to type this out right now. 

And I've also recently posted screenshots of the phone making a call, as well as as call log, showing that I made calls using VoLTE on the AT&T network over the past few days, through the May 2-4 prepaid account drop... in another thread. 

@Nicolas81 .... Your phone has everything necessary to be compatible with AT&T network (depending on the exact variant of model Galaxy A71 you have as far as matching the primary frequency bands)....

Except it does not.   It's missing software for HD voice (voice over LTE)

The AT&T version has a different chipset, Snapdragon 765. The unlocked version came with Snapdragon 730

@formerlyknownas I appreciate your response 

Heres the information I found on the Samsung Galaxy A71 4G. 

@Nicolas81

Where is the AT&T version?   Which is the only a 71 version that is permitted on AT&T.

Your chart does confirm that the non AT&T version came with an older chipset, Snapdragon 730.

The AT&T version is snapdragon 765 and it has 5G, the non AT&T version, as in your chart, does not offer 5G Hardware. 

https://www.att.com/buy/phones/samsung-galaxy-a71-5g-128gb-prism-cube-black.html

You did the IMEI trick before your phone was shut off aka flagged aka suspended correct?  

@formerlyknownas  I appreciate your response. 

Based on what the OP said, I assumed (perhaps mistakenly) that they were talking about the 4G only version of the Samsung Galaxy A71. 

I think that you assumed the same, but only about the Galaxy A71 5G. 

So that's why you didn't see the AT&T variant in the attachment. 

And while I don't think that At&t, or any other carrier, sold the 4G variant.. as you can see, it has all the components necessary to be compatible with the network. 

But you are correct... At&t won't allow it to. 

In that light, if I am correct about the version of the Galaxy A71, then it is much like my Galaxy A70... in that it will work on the network... provided that a IMEI number that At&t system recognizes is registered with the account. 

I want to thank everyone for all the answers and help. I broke down and just bought a prepaid ATT Galaxy A13 5G.

I am keeping the A71, just going to put a Straightalk and/ or Cricket sim in it, as it can have 2 phone lines. I'll use it for a backup, maybe my 2nd business line.