Is my Android asian phone blacklisted?

But it was working just fine the last 2 weeks. T-Mobile changed their bands since 06/05/2024?

I've been using it from the same locations, home and work. It's not working on any of both.

It worked fine since day 1, when I inserted the SIM.

I’ve experienced the same issue with my Xiaomi phones starting yesterday 6/4/24.  They were working on the prior day, but now cannot connect to mobile network.  

Xiaomi Redmi Note 11 5G

Xiaomi Redmi Note 9S
Xiaomi Redmi Note 7

Xiaomi Redmi Note 6 Pro
SIM cards were originally in the Note 11 5G and the Note 7, Swapped SIM cards into the other phones with all of them showing bars but no mobile data. 

Went to a T-mobile store and the rep said that the IMEI’s were “locked to carrier” but was unable to see what carrier they were locked to. They replaced the SIM card on one of the phones and it didn’t resolve the issue, also they placed the SIM card into a T-Mobile phone and it worked fine. 

Just some back info.  All phones were working prior to yesterday on T-mobile.  Phones were purchased at various times from different Amazon vendors. (months to years apart) 
Only mobile data does not work, they can make cellular calls to and from the phones when the SIM card is inserted. 

Side note, I kept one of the SIM cards in the Note 7 and data started working again, was able to run a test to speedtest.net and got 27.xx Mbps download.  Left it over night and in the morning I tried testing the SIM in another Xiaomi, now it doesn’t work again in either the phone I put the SIM into OR the Note  7.  No mobile data but I can make and receive calls. 

Sorry for the thread hijack but I noticed the same issues. 
 

The phones have been working for years until Monday.  The Note 6s was originally purchased back in 2018, and the Note 7 was purchased in 2019 from a different shop.  

*update, the Note 7 is working again with LTE data, but it took over ½ a day to register it back on the mobile network.  I’m wary to swap the SIM card again as it’s probably gonna lose data service again. 

Ok I’m not sure which phone you wanted it for but here are the phones in question:

Xiaomi Redmi Note 11 5G: FCC ID: 2AFZZ16SG

Xiaomi Redmi Note 9S FCC ID: 2AFZZJ6A1G
Xiaomi Redmi Note 7 : FCC ID: 2AFZZ-RMSF7G (phone working with mobile data)

Xiaomi Redmi Note 6 Pro FCC ID: 2AFZZ-RMSE7TH

That document was for the phone’s Ad-Hoc mode which was disabled, (no peer to peer connectivity) there is another document for LTE B40 which I don’t believe the phone is capable of doing.  Other than that, I didn’t see anything that stated that it 5g/LTE service was blocked for the FCC ID for the phone. 

I do appreciate all the assistance from the community!

I was actually addressing the OP @IvanOA  but that’s OK. It’s not always easy to find specs on some of these Chinese phones so having the FCC ID allows me to go to the FCC website (EA database) and look up which US bands and standards it was tested to be in compliance with. The Note 15 5G above seems to have just about every T-Mobile LTE & 5G band except 71. Why it wouldn’t work is kind of a head scratcher.

Getting VoLTE and VoNR to work on them that is compatible with T-Mobile can be why.  Sometimes an update to the device can change the carrier profile, roving compatibility for VoLTE and VoNR that works with T-Mobile USA.  These devices might have the correct bands but VoLTE and or VoNR also needs to be compatible to make and receive calls.  

Although, Currently my Redmi Note 7 is still working on LTE AND is still able to make/receive phone calls. Although I’m still not willing to swap the SIM cards into another phone until I know it’s gonna work properly. 

Yeah. THey never showed. No straight answer from the chat ppl. UGH.

My Xperia 1 III had been working fine since I ported from AT&T to T-Mobile in Feb 2024. Although only one 5G band is available, I've never had any issues with VoLTE or VoNR not working. 4 days ago, on June 7, the phone stopped connecting to the network. I spent hours on the phone with support and another two hours in the store. A new sim did not work either. I've had to use my old Pixel phone as a replacement for now. When I open the diagnostic screen, I watch the phone bounce to every available technology it can find (GSM, LTE, etc.) but it fails to connect. T-Mobile must have pushed a change on their network a few days ago. I am still waiting to hear back on the status of my trouble ticket. 

Networks do change.  With upgrades to the network and areas changing.  Sometimes a band that was deployed in an area is no longer the best option for that coverage and it is changed once the towers are upgraded.  Blacksburg, VA was a good example.  Most of it was band 2 and band 4 a decade ago.  Now it's mostly band 71 with 41 in certain areas.