Do I have to accept a return on an iPhone I sold on eBay?

I sold a Verizon iPhone 4S on eBay on June 6th with a 14 day return policy. I specified in the description that I will only accept a return within this time period if it is not as described. The buyer said he was satisfied with the purchase, however he had T-Mobile. He bought the phone thinking he could activate it on his plan, however he could obviously not and now wants to return it. Do I have to agree to the return or not? It was past the 14 days from date of sale and it was not as if the item wasn't as described, only that it was his mistake. What should I do? Thank you everyone. Here is my listing: http://cgi.ebay.com/...1091593373

NO, you would only have to accept the return if you had not given a 14 day guarantee. If they still want to accept this, you can open a case through ebay and they will make the final decision on whether the phone must be returned.

You do not and should not go against your advertised conditions.
Many buyers on Ebay do not pay enough attention to the conditions and then expect the
seller to fix everything.