I don't understand why AIS wouldn't transmit that data outside the US, or why it wouldn't be usable outside of the US. The primary design purpose for the data being transmitted is letting others knowing where you are in order to avoid collisions, facilitate communication, etc. It was designed to ensure safety of ships from all over the globe, wherever on the globe they might meet.
Although MMSI's that aren't associated with licenses might not be in the international databases, Class A and Class B radios, themselves, still transmits everything they know.
This includes static data, such asMMSI, vessel type, vessel name, call sign, IMO or Official Documentation Number, antenna location, and vessel dimensions.
It also includes voyage data, such as navigation status, draft, destination, and ETA.
What isn't transmitted are things that are only in the database, such as number of life rafts, types of communication equipment aboard, etc.