After coming up through the Tottenham academy, Caulker's career is not your average pathway as he ended up playing in Wales, Scotland, Turkey and now Spain.
It even included a shock loan spell at Liverpool where Jurgen Klopp played the defender as an auxiliary striker.
If his club career saw him travel the world, his international career saw him clock up even more miles after playing for Sierra Leone at the 2021 AFCON.
Despite already playing for England and for Team GB at the 2012 Olympics, the Feltham-born star received a call from the African nation over representing them at the tournament, which had been delayed a year due to the climate and Covid.
After some persuasion from West Ham legend and talkSPORT pundit Carlton Cole, Caulker said yes - and did not regret it for one second.
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He told talkSPORT on Thursday: "It was such an incredible experience. Carlton Cole called me out of the blue about three years ago now.
"He said 'would you consider playing for Sierra Leone?' I said I would but it had never come up on my radar.
"He said 'look, my uncle is there, they've qualified for AFCON, they are really interested in recruiting you and a couple of other boys from Europe to come and bring some experience. Would you up for a conversation?'
"So had the conversation and before I knew it, I was there. I loved it."
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Caulker played all three group matches for Sierra Leone at AFCON that year, though they finished third and crashed out of the tournament.
However, they had a tough group including defending champions Algeria and an Ivory Coast side brimming with talent.
Sierra Leone drew against both before losing to Equatorial Guinea, who leapfrogged above them.
But Caulker came up against a star-studded Ivory Coast team that included Eric Bailly, at Manchester United at the time, and Franck Kessie, who was plying his trade at Barcelona.
The Elephants had gone ahead through Sebastien Haller before Sierra Leone struck back but former Arsenal ace Nicolas Pepe put his nation ahead again.
They thought they had won it but Alhaji Kamara netted a last-gasp equaliser to make sure the points were shared on a brilliant day for Sierra Leone.
However, getting used to life in Sierra Leone, who Caulker qualified for through his paternal grandfather, took some time - and required him to get back to basics.
"It was definitely a bit of a culture shock," the former Spurs, QPR and Liverpool star added.
"When I was over there for my first trip and handed a medium-sized kit, I said I'm extra large! They said that is all we've got.
"We finished training, I went to hand it back and he said that is yours for the week. So where do I wash it? He said the sink!
"I was like 'what!' So coming from England to Sierra Leone where you are washing your own kit, it was a very humbling experience.
"But honestly, the vibes there, the energy. I loved it, I absolutely loved it."
Caulker has gone on to play a total of 13 caps for Sierra Leone and at 32, still makes himself available for selection.
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That is despite taking a new career pathway in Spain as player/manager of Malaga City in the fifth tier of football in the country.
He took the role in December last year and, despite still being young for a coach, is keen to continue his development as a manager.