Area code 844 is a future area code. When one dials 844, the caller is charged for the call
not the number dialed.  When in doubt do not respond !  SCAM

Got a letter in the mail saying I should call this number because I've won 2 round trip airline tickets in the U.S..  I must respond by 4/28 or they will be given to the alternate.  

I don't feel comfortable calling an unidentified exchange 844.