Will I be able to use my unlocked international Samsung phone after February 2022?

Nope. 

  Not on at&t.  And not even now... the last day to activate ineligible phones was January of 2021. 

Attempting to use that phone on AT&T now would only suspend your service until you replace the phone. 

Hello @dddtggh, let's look into if your phone will be compatible after the phasing out of the 3G network. 

You can review the devices that will work on the AT&T network after the shutdown. If the phone is not listed, you wouldn't be able to use that particular device. 

We no longer activate phones that don't support HD Voice since they won't be compatible to work on our network when 3G shuts down.

We hope this information helps, and thanks for reaching out to the Community.

Jeff, AT&T Community Specialist

I just purchased a Samsun Galaxy A32 4G international version. I haven’t opened the box yet because I’m concerned that it might not work. Would an international serial number be on the approved list? It is an unlocked GSM 4G phone.

Its all about the model number  if you don't see it on either list then its not going to work.

Use these lists to find out.  Does not matter what it is.  The phone has to match ATT's magic lists here.

https://www.att.com/es-us/idpassets/images/support/pdf/Service-Capabilities-Unlocked-Devices-ATT-Network.pdf

https://www.att.com/es-us/idpassets/images/support/pdf/Service-Capabilities-Unlocked-Devices-ATT-Network.pdf

Thank you! It’s not on the list (darn!). All of that research down the drain…at least I can return it...

a53 5g from best buy when on sale is a steal.