Users around the United States are seeing a 10.2.1 update push out from the Uncarrier T-mobile but it seems that this is an isolated event due to various models of T-Mobile capable BB10 devices. For instance there are T-Mobile specific Z10s STL100-3, Sub-Model RFF91LW) these devices are not seeing the 10.2.1 update.
However if you own a Z10 STL100-3, Sub model RFK121LW and have an active Tmo SIM you should be seeing the update via Link or OTA to your device.
We apologize about the confusion from the submodels in this release. Those who do have the RFK121Lw model, it seems your device must also be unlocked for the update to be pushed. BlackBerry gave out these models at BlackBerry media events but they were never official Tmo devices (only tmo compatible).
On the side of caution it’s always best to do a backup before jumping into any install. Check your updates within app settings and get the update for yourself but alas those who have purchased their device from Tmobile are not as of yet seeing the update. Word has that Tmo will push this officially mid February, or quite possibly early March.
Thanks Jon! @nerdologist_jon