Okay everyone, after shopping around for an iPhone, I have noticed something over and over again.  Many people sell their iPhones claiming it to be "NEW" are actually refurbished iPhones.  Here are the things to look out for if the item is refurbished:

Honest sellers will say if the phone was refurbished because refurbished iPhones come with a box that's completely white.  On the white box, it will say "Apple Certified".  Chances are if the seller doesn't have a box for the iPhone, there is a strong chance that they purchased the phone as a refurbished unit from Apple's online store or from AT&T's online store. 

Most importantly, ASK FOR THE SERIAL NUMBER!

Well why would it matter?  First off, for MOST of Apple's products, especially the iPhone, the serial number will start with a 5K.  If the serial number starts with that for an iPhone, then it's guaranteed to be refurbished. 

New iPhones have either a 7k or 8k.  The 4th digit of the serial number means the week of the year it was manufactured.  So for an example, if it's 8k801xxxxx then it means the phone was produced it was manufactured the first week of 2008.  7k745 would mean that the iPhone was manufactured on the 45th week of 2007. 

Also just so everyone knows, Apple will not honor the warranty if you have an "unlocked" phone.  It's very hard to obtain support for the phone if you can't provide the receipt.  It is possible, but difficult because "unlocking" is breaking Apple's TOS.

When an iPhone has been unlocked, the total usage time for the phone has also been cleared out.  So the true way to determine how old the phone is, is to ask for the serial number.  If the seller isn't willing to give out the full serial number, it's fine.  As long as it includes the first 5 digits!

Be safe!