What is a regional blockade in a Samsung device?
Region blockade is a type of blockade which stops the device from working in different networks, other than the ones mentioned on the information sticker. Samsung smartphone is compatible only with region specific networks.
For example if a Samsung device is prepared to work only on European networks, other regions like USA or Asia won't work. After inserting a simcard from USA, the device will ask for a RGCK code or a network unlock code. USA is a different region, and it won't work even though there is no network blockade on the device.
In order to remove such blockde you need to use a RGCK code (regional blockade code). RGCK code is available in this service.