It's a maritime term, as used in the idiom "port of call".

That doesn't even seem old fashioned. It's the same sense as, "I'm coming home, but I'll call at the store on the way."

is that still common in UK English? in contemporary US English 'call' seems almost exclusively used for 'telephone calls', i imagine a good proportion of the population being unfamiliar with the idea of 'call' indicating a physical appearance of any sort

In the UK "popped in" is still used a lot e.g. "I popped in to Tesco on the way home"