Older Samsung phones utilized a 16-digit "master code." The 1.0-v tool effectively injected a null control key or overwrote the lock counter (attempts remaining) to zero, tricking the baseband into accepting any SIM card.
The software operates by putting the Samsung device into a specific diagnostic mode (often ODIN Mode or Download Mode). sim-unlocker odin 1.0-v
If you are trying to unlock an old Samsung for nostalgia: Older Samsung phones utilized a 16-digit "master code