You can also try to log on to your favorite web site (other than Amazon or Wiki). The Global Wireless is very restrictive as to what web sites you can get to (at least up here in Canada).
That won't work in the US.

When did you buy it? Before a certain date they only sold US (Sprint) Kindles and after a certain date they only sold Global (ATT). (Exception, the US Kindles were sold as refurbished units after they switched to Global.)
Also, did YOU buy they Kindle? Go to your order page. It'll say what the product was called at the time you bought it and you should be able to figure it out from that. Especially if you click it to go back to the original product page. I just tried that and it still shows the K1 page and then references to newer models.