Just to share my experience, I was having wifi weak signal issues with my phone. Called AppleCare, and they told me to take it into a genius and get it swapped. The genius first brought out a phone in the white box. I immediately noticed what looked like scribbles and letters on the back of the phone. The genius stated that it looked like a little kids handwriting. He had one more in stock in a white box, luckily I did not see any major scratches. Genius told me these phones are "rebuilt." The replacement has Nd model number. I looked up the serial number to see when the phone was built. Week 36 in chengdu. It originally listed the model number beginning with md. all ND phones are def. rebuilt/refurbs. Don't let anyone fool you. Now I am stuck with a refurb after having a brand new one for a week