There is an international treaty (Vienna Convention) that requires governments to inform arrestees of their right to speak to their embassy. The problem is that treaty violations aren't really enforceable without an underlying local statute to implement them.
It was only recently that Illinois made it a statutory requirement to implement the treaty by adding "(b-5) This subsection is intended to implement and be interpreted consistently with the Vienna Convention on Consular Relations, to which the United States is a party." to their arrest law:
https://www.ilga.gov/legislation/ilcs/fulltext.asp?DocName=0...