How to unlock an Iphone 4 I got from Germany to work in the states?

When I lived in Germany I bought an Iphone 4. The lady told me I would be able to use it in the states… Well I can't. How do I go about getting it unlocked for the states?

Jailbreak it… Then get an unlocking app via cydia

Iphone

Get a Permanent unlock at http://attiphoneunlocker.com/
You can get jailbreak & unlock at http://unlockiphone-4s.net/

If ot baseband 1.59 then it can be unlocked by jailbreaking via software.

Go to http://iphoneunlocksoftwarefree.com you can unlock it free of charge

If you want to use your iphone in United States first you have to remove the
network lock. Then you can use any local gsm simcard on your phone.
You can unlock your iphone 4 using the remote unlock method. Get
the remote unlock services from the site http://www.Onlinegsmunlock.com
and unlock it easily.