How do you check if AppleCare is used or not?

[h4mza]

I bought AppleCare on ebay cheap, the seller listed it as parts or not working as he is not sure whether its used or not, and hes not sure if its compatible for iPhone 3 or 4.

How do i find this out, what do i need to ask him?

 

[Applejuiced]

If the code inside is already used for another device then it's useless.
I wouldn't waste my time.