Unlocked s21 Ultra showing as "Unknown Device" and not supporting 5G or Extended Range LTE on My Mobile account

syaoran wrote:

Gamegrrl wrote:

So why does customer support keep leading me to believe this is a "glitch" and a "fixable" thing. And that I should expect it to be remedied within 48 to 72 hours?

I wish I knew.  Support and Customer Care sometimes say things just to get people off of the phone without being more annoyed than when they called.  Your device showing as an unknown device does not restrict it in any way.  If the device is capable of using T-Mobile's implementation of it, it will work as long as the appropriate settings are correct. 

I have had multiple unlocked phones purchase elsewhere and used on T-Mobile where my account was able to identify the device and IMEI numbers. One device even got purchased internationally and had the details on my account. Yet some other devices, T-Mobile my account page recognized that it was a 'Galaxy S10' but nothing else about the phone or compatibility section.