Owners of the Samsung Galaxy S3 and the Samsung Galaxy Note 2 will be pleased to hear that the devices can be unlocked and when they have been unlocked people can use them anywhere in the world and choose which carrier they want to use with their handset.
Those in the US who purchased the Samsung Galaxy S3 from AT&T know that the handset is locked to the carrier. If they want to use it with another carrier then they have to get the handset unlocked. The device could then be sent to a relative abroad or the user would be able to take it on holiday without any issues. So if you want to unlock your handset, here is how you do it.
Put a different SIM to your own into the handset and then turn off the handset and switch it back on with that SIM inside.
Go to the dial pad on your phone and then type in *#197328640#.
Head over to the Main Menu of the device >  UMTS >  Debug Screen >  Phone Control >  Network Lock > Options Perso SHA256 OFF > and wait for around 30 seconds.
You should then head to Menu and choose Back, where you will come across the Network Lock. Choose  NW Lock NV Data INITIALLIZ.
Just to make sure that no mistake has been made you need to enter Asterisk Pound One Nine Seven Three Two Eight Six Four Zero Pound. There are some people that call the asterisk key the star key and others could call the pound key the hash key.
If all has gone well then you should have unlocked the Samsung Galaxy S3 or any other handset, such as the Samsung Galaxy Note 2. This means that the device should work with any carrier when you insert the SIM card. Samsung have been known to have used this code for some time and therefore it could work with other devices too. Try it you have nothing to lose.