Though he has been in fine form since joining Cardiff City, the centre-back was overlooked for Roy Hodgson's squad and remains free to switch national allegiances
The defender, who previously played and scored for the Three Lions in November 2012's friendly defeat to Sweden, is eligible to turn out for Gordon Strachan's side through his grandmother.
Though disappointed not to be summoned for Roy Hodgson's side for friendlies against Chile and Germany, Caulker remains optimistic about returning for the country of his birth.
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"You've always got to continue to believe in yourself. If you play well then you never know, the call might come."
Scotland assistant coach Mark McGhee was unable to shed any light on whether or not Caulker has yet been approached but confirmed that the defender is on Strachan's radar.
"He's someone who does [meet the criteria to switch national allegiences] as I understand it," McGhee remarked.
"We know who the boy is - we knew him before when he was at Tottenham. I don't know any more than that."