I just bought a second iPhone for my sister on the net for almost no money. And when I got the iPhone today, I see why.

It's a (German) iPhone on 5.1. He's locked (he only accepts the SIM provided by the provider) and still on the introduction screen (where you have to set the language, locations,... you know what I mean.

Since jailbreaking/unlocking iPhone isn't new for me, I tried already a lot. 

 - I tried downgrading it to 4.3, but according to RedSn0w I can't get him into DFU modus.
 - Restoring using iTunes didn't work out either because iTunes is asking for a valid SIM card.
 - Selecting a custom ipsw using iTunes didn't work out either. I guess the baseband to high.

I also know it's next to impossible to unlock such a device. But I'm sure someone in this community knows a way around.

I'm prepared to give 50 reputation (whenever I can) to whom can guide me to install the iPhone (so I actually can use it and see the beginscreen) and another 50 to whom can tell me how to unlock this device. 

So any suggestions at all are most welcome!