If you are in possession of a Samsung Galaxy S, either the Vibrant (T-Mobile) or Captivate (AT&T) model, then you will be interested to know that unlock codes are now available, allowing you to switch between both carriers if you like.
As reported from Engadget, a full unlock method has been revealed courtesy of XDA-Developers. Interestingly, they discovered that the codes needed to unlock the device are actually hidden inside the handset files, and can be viewed with a script and a hex editor.
Engadget has tested the method on both the Samsung Captivate and Vibrant and they have confirmed that the guide works both ways. So if you are looking to switch carrier on your Galaxy S, then this guide is all you need.
A full tutorial can be seen here – let us know if it helped you.