This Garmin VHF 200 radio came with a used boat, and [the radio] has an international MMSI. I can't transfer the number from the previous owner...
Generally a maritime mobile service identity (MMSI) is assigned to a boat, not to individual radios. If you bought the boat and the radio came with the boat, and the radio has the MMSI associated with that boat, then the radio does not need to be changed.
The construction of an MMSI is in accordance with
Recommendation ITU-R M.585-8 "Assignment and use of identities in the maritime mobile service."
Assignment of MMSI to a ship is encoded as follows:
--the first three digits represent the "MID" or maritime identification. The MID denotes the administration having jurisdiction over the ship station so identified.
--the next six digits are referred to as the "ship station number"
All MMSI are "international", that is, they work on a global basis. When you describe the MMSI for this radio (or for the whole boat) as "international" I am not clear on your meaning. Let me inquire:
Q1: do you mean the first three digits (the MID) identify an administration jurisdiction that is not the United States of America?
You can look-up MID codes online at an ITU website:
https://www.itu.int/en/ITU-R/terrestrial/fmd/Pages/mid.aspxNote that MID codes assigned to the USA for North America are 303 (Alaska), 358 (Puerto Rico), 366, 367, 368, and 369 (no special location), 379 (U.S. Virgin Islands)
If the radio MMSI begins 336, 337, 338, or 339, then the registration is appropriate for USA mainland, and you should be able to transfer the registration to you as the new vessel owner.
If the radio MMSI begins with another MID code, then you need to get a new MMSI for the vessel, and then, of course, enter the new MMSI into any radio on the vessel.
Q1: or, do you mean the MMSI ends in a zero?
An MMSI that ends in a zero but has a MID for a USA mainland administration is most likely an MMSI issued by the FCC which generally also almost always means there is an FCC-issued ship station license. You can transfer the registration of an FCC issued MMSI and also the FCC ship station license by filing the proper forms with the FCC. It won't be free.
Let me know the actual MMSI--well at least the first three digits and the last digit--so this problem can be made more clear.
ASIDE: And welcome back. Your participation, particularly in the SMALL BOAT ELECTRICAL forums, has been missed.