Iphone number storage

I finally have an iphone again. A used 2g one, not 3g. While the whole experience was generally a pain, I was happy to find out one thing about the iphone. When you lose your phone, you don't lose your phone numbers. Usually whenever I lose a phone I spend weeks chasing around the phone number of everyone I know. With the iphone however I just had to tell my computer to restore my old settings on this iphone and sure enough it gave me all my phone numbers without any trouble.