You can receive FM transmission anywhere in the world, but if you do it using a marine VHF radio, you need a certificate (ROC) (or RR in the US). If you have a radio installed on the boat and you don,t have the certificate and the CG checks you, you will be subject to a fine. Btw. even a portable VHF radio requires a certificate. I understand that the reasoning behind it is that there are way too many people who use VHF and have no clue how to.
Another btw. the RR (or ROC) does not include the MMSI, because it (RR/ROC) is an individual certificate, not a licence for the radio. You program the MMSI into the radio and it identifies the vessel, not the operator.
And as far as I know, there are no domestic and international MMSI; rather, the differnce is only in how they are recorded (registered) - the "international" one is recorded with the Coast Guard, so it is available to the rest of the world, as well. The easy thing on Canada is that there are no distinction and you get the MMSI number from Transport Canada and it is valid in Canada and abroad.