but if it's not the model the carrier supports it won't work.

Seller declined any support, but were not obligated to provide support since the device failed after the warranty period.

But essentially the unlocked phone is locked to t-mobile compatible networks.

I expected the USA version A1662, as it listed AT&T, Verizon, and T-Mobile as supported.

I got a t-mobile compatible sim card and so far it works well.