TMobile is kicking old Android phones off their network in January because vendors have abandoned the hardware and they no longer get security updates. Android's model of forcing you to buy new hardware every few years to get security updates is broken. https://www.tmonews.com/2020/12/t-mobile-will-no-longer-support-devices-january/
@kyle If this applies to these devices even when they're not running Android, that would be a real pain - the OnePlus One is still one of the best devices to run Ubuntu Touch on as a daily driver.
@jfred I don't know how Tmobile would know which OS is running, and I doubt they'd add that kind of nuance to their policy.