The T-Mobile OnePlus 6T is carrier-locked and doesn't support dual-SIM

Just as expected, the OnePlus 6T is offered in three storage configurations and two colors. However, T-Mobile has confirmed that it will only be offering the 8/128GB model in Midnight Black for $579 – customers can acquire it for just $279 by trading in their old phones. This particular device is identical to the unlocked variant in every way except one.

OnePlus fans who choose to purchase the unlocked OnePlus 6T will gain access to a dual-SIM card slot that now also supports Verizon SIMs, meaning owners can connect to Big Red’s LTE network. However, customers who choose to acquire the OnePlus 6T through T-Mobile will not have this advantage. This is because the device will support just one nano-SIM card and will also arrive carrier-locked, which means it won’t be compatible with other networks. 

 
There’s no doubt some OnePlus fans may see this as a significant drawback that could push them towards the unlocked model. But the company itself doesn’t appear to be too worried. After all, in a post-event interview, it stated that it’s still “very rare for US users to utilize dual-SIM.” Therefore, the OnePlus 6T should “satisfy” the needs of most T-Mobile customers.