1 - Switch ON your Samsung SGH-C207 with a NOT ACCEPTED SIM Card.
2 - Samsung SGH-C207 will ask for "Password".
3 - Enter the Unlock Code.
OR (if the Samsung SGH-C207 shows "Insert Correct SIM Card")
Method 2:
1 - Switch ON your Samsung SGH-C207 with a NOT ACCEPTED SIM Card.
2 - Don't bother about what's being displayed on your Samsung SGH-C207.
3 - Compose : #0111*CODE#.