Need help figuring out this phone.

Hi my name is Josh and I'm from the US.

My sister just bought a phone and was told it was the Samsung Galaxy S 4g. But i have questions about it.

First off ive been looking at the phone and here's the issue.

It has the battery cover from the vibrant.

Also it says vibrant when it powers up.

The main menu looks totally different that the Vibrant or Galaxy S 4g.

But it does have the camera on the front.

The person who sold her the phone told her it was unlocked but now sure really sure.

Here is picture of the main page and menu page:



What i would really like to figure out is if this is in fact a Galaxy S 4g and if so how to i put it back to the original factory settings?

Thanks in advance!