Samsung Galaxy Note III was the first phone produced by Samsung which was released with region lock, and it happened five years ago. Thereafter all phones released by Samsung have this lock. All devices are compatible only with SIM cards of mobile operators which are working in region mentioned on sticker located on box in which was our phone when we bought it.
If phone will be activated with SIM card from correct mobile operator then device will work correctly, but if there will be a problem with our SIM card it's necessary to go to service center authorized by Samsung where you will be able to unlock your smartphone. It's worth having this information in mind especially when we decide to import Samsung's devices.