Cnet Crave had an interesting FAQ
Q: Let's say I bought my iPhone last year and I want the 3G iPhone. Can I give my old iPhone to my sister or sell it on eBay?
A:No, once an existing iPhone user activates service for an iPhone 3G, their first-generation handset will be unusable as a phone. You won't be able to replace it with another AT&T SIM card and use it to make calls. This also means that you can't buy an old iPhone on eBay and expect to activate it on AT&T's network. You can, however, use it as a media player and a Wi-Fi device for browsing the Web.
Is this true?
I sold mine on eBay(Unlocked and Jailbroken). So will the buyer be able to use it?
Q: Let's say I bought my iPhone last year and I want the 3G iPhone. Can I give my old iPhone to my sister or sell it on eBay?
A:No, once an existing iPhone user activates service for an iPhone 3G, their first-generation handset will be unusable as a phone. You won't be able to replace it with another AT&T SIM card and use it to make calls. This also means that you can't buy an old iPhone on eBay and expect to activate it on AT&T's network. You can, however, use it as a media player and a Wi-Fi device for browsing the Web.
Is this true?
I sold mine on eBay(Unlocked and Jailbroken). So will the buyer be able to use it?