I just received this same letter. It came postmarked Phoenix, AZ, no return address. That alone should tell a person it is a fraud.
Received a letter with a bogus airline name saying I'd won tickets, and giving no other contact info than this phone number. Didn't call them. It's obvious b.s., but I worry about others falling for it. Found an article on this:
http://www.bbb.org/blog/2012/07/scammers-lure ... -plane-tickets/