A free app for Android, by Widget7.
The Operator Setting app will help you to switch carriers without having to change your phone number. It will also let you know if your phone is compatible with the network you are switching to. You can also find out whether your phone is unlocked. To use the app, you first need to install it.
To switch carriers, all you need to do is to tap on the “Switch Carrier” button. You can also find the switch carrier option on the main menu of the app.
To check the compatibility, first launch the app and tap on the “Check Compatibiity” button.