Black I607 Jack Samsung Sgh

My friend gave me this phone because he thought it was too complicated, but when I put my SIM card, the display shows
"This phone can be used with a SIM card specific. Enter the unlock code or insert a SIM card approved"
We do not know the code and I do not know how to override this.
Is there an online program that I can use to unlock it, or what?
Please help because I need this phone since my other was stolen.

You can either pay a Web site for software programming to do so or the frugal option would be to have a friend who has AT & T ATT technical support call 1-888-892-9760 opt. 1 and request the unlock code for the phone. They will need the IMEI of the phone that should be on the sticker below the battery. If technical support why your friend needs to unlock said "I'm traveling to (a county in Europe) and where I'll stay where I do not get service with AT & T. I will use the local Prepaid over there. "Then, the support should email you the unlock code.