Problems while trying to unlock

[noob with iphone]

Hey,
My uncle give me his iphone 3 (i think gs), i only have the phone, no other details.
When i start the phone, there's a pictures where it says to connect with itunes. or that only emergency calls are able to use.
Itunes just says: "The SIM card inserted in this iPhone does not appear to be supported."
I put it into the DFU mode, but after loading the same continues....
It's my first time trying to unlock a mobile phone, so pls help.
[Sorry for my english ^^, i hope you understand everything...]
If you want more details about the iPhone you have to say how to get the informations.

Thanks.

[HottSushiz]

So you have no idea what firmware or baseband it could be on?