If the celphone that you bought here in Qatar is a Tri Band or Quad Band, yes you can use it in USA,but if its a dual band...sorry you can not use it.Qtel provides roaming in USA.I suggest that you use only your Qtel roaming in receiving messages cz the rates in USA is so cheap compare to Qtel rates, you just need to buy a phone card for 5 US$ & you can call your friends where ever they are...