The doctorDoctor was in tranzalorTrenzalore, with Clara but it was truth domed. As in the whole city of Christmas ( truetrue name in the future: trenzaloreTrenzalore) was in the truth trance. So check for the " in the fields of trenzalore"Trenzalore" and " where no living creature can speak falsely or fail to give answer"
A question was asked through a transistor which was transmitted all across the universe. From galafreianGallifreyan origin. From the crack in trenzaloreTrenzalore. And was translated, the message was: "Doctor Who"
It was his future self in the past trenzaloreTrenzalore. Trying to make a difference.