But the French and Dutch held islands in the Caribbean also decided that
> they would prefer to be masters of their own numbering/dialing destiny,
> and chose to get their own ITU country codes rather than be part of
> area code 809 in Country Code +1.
There's a tiny island within Canada near Newfoundland, St. Pierre/Miquelon, that is part of France and is reached by dialing international codes.
I suppose keeping this island under France instead of Canada is a matter of nationalistic pride, but I suspect the overall administrative costs of running an island like that as a separate country are enormous.