My bet is that this is a Chinese "new" N900.
These are not new in any sense except that the outer plastic has been replaced. You get a nasty old repaired Nokia Board that has been junked and repaired. I bought one on eBay and it had old contacts and apps still installed. Reflashing to fix non functioning apps took every trick on TMO to even start and at 45% bricked the phone, it wont enter flash mode. Some Chinese repaired "new" N900s may work fine as they only had to fix the USB but they are still worn out and abused to the point of breakage old electronics inside fresh new plastic.

My advice, don't buy phones from someone you dont know in China.