iPhone 8+ Unlocking Help

Hello all, I'm attempting to unlock my iPhone 8+ from the original carrier (Sprint) so that I may use it with a different carrier SIM (Metro PCS).

I've already spoken at length with Sprint and according to their side of things, the device has already been unlocked. However when I insert my Metro SIM card into my iPhone, the device reads "No Service".

I've already factory reset the device, as well as reset network settings. Still no luck.

Any and all advice is welcome. Thanks in advance.