The 21-year-old, who has one Three Lions cap to his name, was left out of Roy Hodgson's squad for the upcoming international friendlies against Chile and Germany.
"I think you've got to have hope and anything can happen with football as we've seen over the years," BBC Sport quotes Caulker as saying.
"You've always got to continue to believe in yourself. If you play well then you never know, the call might come.
"Obviously I would have loved to have had the call, but it's not disappointing as I can get the rest and look to build on the performances for Cardiff."
Caulker scored on his England debut against Sweden in November last year.