I lost my iphone 4s! What can i do?

I don't know where i left it and now i'm phoneless. I have a only at&t flip phone that i used before. Can i use that one? Can i go to att and will they change my plan and give me the sim for the phone?

Yes you can and call your operator to block it

Call them and see. You will have to call them anyways to shut the lost phone off in case someone found it and decides to use it. There fore racking up your bill and having free service in the process. Tip: Backtrack your moves and see where you may have been and search.