The whole subject of whether you should unlock your device from carrier restrictions while under contract is debatable. However, it does have legitimate use case scenarios such as switching to another carrier while travelling in areas where your carrier doesn’t provide adequate coverage. After all, who doesn’t want to avoid hefty roaming charges when travelling abroad?
If you have the Sprint variant of Samsung Galaxy S III and want to switch to another carrier, you’re in luck! XDA Forum Member pid1981 shared a method that lets you change the SPC code on the to 000000, allowing you to use your Sprint Galaxy S3 with other CDMA carriers that support the device.
You can find the complete method in the forum thread. Although it isn’t exactly aimed at newbies, it should be simple enough to follow if you don’t mind doing a radio downgrade, some hex editing, and a radio upgrade._________