[Q] SIM unlock Sprint HTC One M8 topic

I have the SPC and SIM unlock code for my HTC One M8 for Sprint. I cant figure out how to unlock it. When I put a TMobile SIM in, the phone does not ask for the code. Instead, a warning shows 4G services are unavailable as the SIM/UICC is invalid. Im new to this, so any help would be appreciated.