Unlocked T-Mobile S22 Ultra won't flash over to AT&T

[userAvaIHjm2rP]

Why won't my unlocked s22 ultra flash over to att?? It's still stuck on the T-Mobile screens and even shows the 5G banner for T-Mobile but everything works perfectly fine on att

[user3ftC5dkFO9]

I would try searching "reset network settings" under the phones settings. Then restarting your device with the ATT sim.

[LongHiker · Accepted solution]

@userAvaIHjm2rP Your phone won't automatically change firmware from one carrier to another when switching the SIM card. The only change that occurs is that the new carrier's network settings are loaded into your phone. 

To replace the T-Mobile firmware, you would need to flash the phone with AT&T firmware. 

[userAvaIHjm2rP]

They always have changed firmware when unlocking and changing sims. I work for ATT and can confirm this.

[LongHiker]

@userAvaIHjm2rP In the store perhaps the personnel have done it.

Changing SIMs by itself will not cause it to happen. 

[userAvaIHjm2rP]

I am the personnel in the store.. I'm the worker.. I have experienced this first hand numerous times. But it didn't happen to mine when I got it. It's strange

[Loonie01]

Go over to XDA developers website. You'll get the answers there.