GalaxSim Unlock is an app that lets you unlock your Samsung Galaxy (S, S2, S3, some S4, Tab, Tab2, Note, and other models), so you can use them with other mobile network operators.
The app includes two key features. The first one lets you make a backup of your Android's EFS folder for free. The second one, available for purchase, lets you unlock your device. Of course, before doing so, you can take a look at a detailed message about unlocking the device.
Only owners of a locked Samsung device would be interested in GalaxSim Unlock. If that's your case, it might be a good idea to take a look at the possibilities this app can offer.
