best phone for ATT new generation 4g and 5g networks

@Nicolas81,
So, I changed my phone to another one from the whitelist. I got Pixel 6 Pro (G8VOU), then changed IMEI in my ATT account and everything worked just fine... first 2 days (including 5G network).
After that I got a message - "SIM is not prepared by MM #2". My ATT number was no longer associated with a user ID and the ATT account was suspended. I went to the local ATT store but was told that I should call the 611 call center (but my phone was blocked!).
I called them from an another number, explained the situation, and they told me that the whitelist is for reference only and doesn't guarantee that a phone will work, in order it to work you must to buy a phone in ATT store or from their authorized dealers and this phone must be locked to the ATT network.

Now I don't know what should I do, buy another locked phone? Seriously?

I'm totally in shock. The whitelist looks like a bad joke. USA phone made for USA doesn't work in USA (I mean Pixel 6 Pro) :)

@bl00dcat 

Someone is giving you a line of bull.  I change phones like water.

@GLIMMERMAN76 

Tomorrow I will go to another local ATT store and maybe they can help me. I hope so.

@bl00dcat I appreciate your response. 

And thanks for the update. Appreciate it. 

I have been debating on whether or not to start a new prepaid account... with a compatible IMEI number.. just to see how long it takes for At&t to shut it down. 

So the going rate is two days now, huh? 😄

Once again, IMO...this proves that devices can work on their network... that is... until At&t decides to restrict the phone or drop the account. 

And as far as what the customer service representative told you... that's exactly the point I was making earlier... none of them know what they are doing. 

And are simultaneously telling the truth... you have to buy from At&t directly. 

It matters just as much about whether or not the representative is giving correct information... as it does that they are giving out information... as the "experts" ... that customers will believe... because what choice do they have?

Having said that, unfortunately @GLIMMERMAN76 @formerlyknownas are right... no matter how many times or ways you prove it, and/or prove them wrong... none of it will carry enough weight to make At&t change it's practice. 

@bl00dcat 

My apologies... I just realized that I didn't post it in this thread... my prepaid account... on a Samsung Galaxy A70... that had been opened since late February... was dropped May 6th.