I have to write this to support the original poster
The exact same thing happened to me.
I sold the phone, the guy wanted me to ship it to Russia. I said no. He then said he wanted me to ship it to a california address on his paypal account even though his ebay profile said he was in minnesota
I ship it, insure it, give him the tracking info. 2 days later he signs for it. I have proof he signed for it. I hear nothing from him for the next 10 days. PayPal has a hold on the money, so I ask him for feedback so they will release the money. He then immediately files a complaint with ebay saying the box was empty.
It's been several weeks now, I've filed a claim with the shipping company, and am waiting for feedback. EBay said the resolution was for the buyer to return the phone to me and for me to refund his money but I have reiterated to them that this solution doesn't work because he has no phone to send me (supposedly)