will a unlocked sonim xp3 phone work for t-mobile after january 1 2022

To add to the confusion (as one of the owners of a Sprint-obtained Sonim XP3 flip phone):

-----------------the saga continues --------------------------

Today I got an email from t-mobile saying after July 1 when 3G shuts down it would not work, and to click on a link in the email to get a free OnePlus NORD N200 5G phone. On logging onto my account with/through that link I found myself in my account but with no access to any upgrade.

I called t-mobile customer service and first complained that I believed the notice that my phone would stop working after 3G shutdown was incorrect… that in fact it is 4G LTE compatible.

After quite some time she confirmed that.

Then I said, basically, well, if I can get a free upgrade to a 5G phone, let's go ahead and do that. But I want a flip phone. Response was "if you want a flip phone upgrade/trade-in you'll have to pay for it. So I scratched that, and said "Send me the free 5G phone." Well, turns out even that is a shell game.. they switched that from the NORD to a Revvl 5G. I said, OK send that. Then it was "there will be  $35 charge." Huh? When is free $35…. but I said OK, proceed, and was prepared to let them put a $35 charge or give them a credit card. Well, at this point I've been on hold with the rep for about 30 minutes with her saying things like "please hold while I work on this."  She has twice sent me temporary PINs.

Seems like a complete FUBAR with their "free upgrades" … at least in my experience with this one t-mobile account… and even worse with my two legacy Sprint accounts.  Finally I just told her to forget it… She said take my old phone into a t-mobile store and do a trade in there. We'll see. Don't hold your breath.