Currently Being ModeratedJan 14, 2013 5:45 AM (in response to yaderzkaya)
The phone is carrier locked to a carrier other than the one you are trying to use.
If the seller on ebay claimed it was unlocked, they lied. File a claim with ebay and get your money back.
Currently Being ModeratedJan 14, 2013 5:48 AM (in response to yaderzkaya)
In order to trust that an iPhone is carrier unlocked you really need to purchase directly from Apple. KiltedTim is probably right that the seller lied.