What does this phrasal verb mean: 'call in at'?

Test No. [color=blue]incompl/advan-83 “GMAT Verbal Quiz (6)”, question 3

For the first time in his life of going straight home, he called in at a pub on the way back.

(a) instead
(b) inside
© including
(d) into

Test No. [color=blue]incompl/advan-83 “GMAT Verbal Quiz (6)”, answer 3

For the first time in his life instead of going straight home, he called in at a pub on the way back.

Correct answer: (a) instead

Your answer was: [color=green]correct
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“Call in” here might mean to visit?

Yes, call in does mean visit but when you have an object you need to add at as in: Call in at our house.