AIS codes · MMSI formats
MMSI formats: who is transmitting?
An MMSI is nine digits, and its first digits say what kind of station it belongs to. Only ship stations carry their flag in the first three. Every other format puts the country somewhere else — or has none.
| Pattern | Station | Country digits | Heard now |
|---|---|---|---|
| MIDxxxxxx | Ship station | Digits 1 to 3 | — |
| 00MIDxxxx | Coast station | Digits 3 to 5 | — |
| 0MIDxxxxx | Group of ships | Digits 2 to 4 | — |
| 111MIDxxx | SAR aircraft | Digits 4 to 6 | — |
| 99MIDxxxx | Aid to navigation | Digits 3 to 5 | — |
| 98MIDxxxx | Craft associated with a parent ship | Digits 3 to 5 | — |
| 970xxyyyy | AIS-SART (search and rescue transmitter) | None — xx is the manufacturer, yyyy a serial | — |
| 972xxyyyy | Man-overboard device | None — xx is the manufacturer, yyyy a serial | — |
| 974xxyyyy | EPIRB with AIS | None — xx is the manufacturer, yyyy a serial | — |
| 8MIDxxxxx | Handheld VHF with DSC and GNSS | Digits 2 to 4 | — |
Formats are defined in ITU-R M.585. “MID” is the three-digit Maritime Identification Digits code the ITU allocates to each administration — see the flag state directory for every MID. Counts are identities in our latest snapshot; a coast station or AtoN appears there because it transmits in the same format as ships.