cant use different sim card

i did get tired of the i-phone so i gave it to a friend...but now i see that even after you unlock an i-phone diffrent sim cards dont work.you have to verginize the phone then re-unlock it! i didnt know that so i really messed up the phone so im gonna go to apple an see if they can return the phone. then i will have a brand new one that i can unlock will update on unlocking the new upgraded system .all my love..