I had the same problem with my Treo 650. Also an Ebay purchase. The seller no longer is active with Ebay. After giving my CSR the esn # she told me to wait a little while before using the phone. I waited, waited, & waited. I finally called them back & was informed the ESN# was no good! Why wasn't I informed the 1st time? So I was advised to go to a Sprint store and speak to a manager. Have the manager contact the supposed owner and ask if they were still interested in the phone. Well that took almost a week & a half. He was never there or too busy or he couldn't contact the supposed owner. When he finally claimed to have contacted the person...according to him(manager), the person said he didn't even know his phone was missing! I decided to press the voicemail key and got a number that I decided to call on my own. There was a voicemail with the person's name which was the same name on the screen at the Sprint office BUT he stated "you have reached the Sprint office"! Now I'm thinking scam. I was once told of bad esn# phones being sold then the phone being returned to the previous owners once confiscated and they can sell again & collect monies on the same phone again. Or the insurance scam when a person wants an upgrade & reports their phone stolen. What can I do?