Just stuck my T-Mobile SIM into a Sprint iPhone XR and it worked. Saw someone say they did it to their S20 and saw the same thing. I'm so glad I can
T-Mobile Customers Can Score an iPhone on Us - T-Mobile Newsroom
The iPhone XR at Metro | Switch to Metro and get the iPhone XR for under $50! Treat yourself to the gift everyone wants. | By Metro by T-Mobile | Facebook
Used Apple iPhone XR - 128GB - Verizon + GSM Unlocked T-Mobile AT&T 4G LTE- Coral - Walmart.com