Coast station MMSI (00MIDxxxx)

What it identifies

Two leading zeros identify a coast station: a shore-based AIS base station, a vessel traffic service (VTS) centre, a port authority or a coastguard radio station. They transmit on the same channels and in the same format as ships, so they show up in raw AIS feeds alongside vessels.

How to read it

The MID follows the two zeros. Reading the first three digits as a flag gives "00x", which is nonsense; reading digits 3 to 5 gives the administration that operates the station. Coast stations do not move — a "vessel" that never moves and has an MMSI starting 00 is shore infrastructure.

Does it give a flag?

Not a flag — a coast station has a country, read from digits 3 to 5, but it is not a ship.

Every vessel page on this site works this out before printing a flag. Where the MMSI is not a ship station, the page names the kind of station instead — a wrong flag is worse than an honest “this is a coast station”.

All MMSI formats

Have a number to check? The MMSI decoder applies these rules to any nine digits. For the background, read Reading an MMSI.