• MMIS Overview
• How To Obtain an MMSI Assignment
• MMSI Format

MMSI Overview

Maritime Mobile Service Identities (MMSIs) are nine digit numbers used by maritime digital selective calling (DSC), automatic identification systems (AIS) and certain other equipment to uniquely identify a ship or a coast radio station. MMSIs are regulated and managed internationally by the International Telecommunications Union in Geneva, Switzerland, just as radio call signs are regulated. The MMSI format and use is documented in Article 19 of the ITU Radio Regulations and ITU-R Recommendation M.585-4, available from the ITU.

How To Obtain an MMSI Assignment

U.S. Non-Federal User

In order to obtain an MMSI, commercial users, or those who travel outside the U.S. or Canada, must apply to the Federal Communications Commission for a ship station license or an amendment to a ship station license. State and local governments generally obtain an FCC ship station license at no charge. All vessels required to carry a shipboard radio or which travel outside the U.S. are required to have an FCC ship station license.

Non-commercial users (e.g. recreational boaters) who stay in U.S. waters can obtain an MMSI through approved organizations such as BOAT US 1-800-563-1536, SEA TOW 1-800-4SEATOW, U.S. Power Squadron, and Shine Micro (primarily for AIS). Most of these organizations provide MMSIs at no charge even to nonmembers.

U.S. Federal User

Federal users can obtain MMSI assignments from their agency radio spectrum management office in accordance with Section 6.6 of the NTIA Manual. US Coast Guard users operating DSC or AIS equipment under official orders can obtain an MMSI through Commandant (CG-622) in accordance with Commandant Instruction M2000.3D, Section 11.D. U.S. Coast Auxiliary surface vessel operators should request assignment of MMSIs using the same method as for a U.S. Non-Federal user.

Obtaining MMSIs for DSC-equipped VHF Handhelds

VHF handhelds used in the United States should use the MMSI assigned to the ship to which the handheld is primarily associated, even if another radio on that ship uses the same MMSI. Non-commercial users of VHF handhelds not primarily associated with any single ship may use an MMSI provided by an organization such as BOAT US, SEA TOW and U.S. Power Squadron (see above). VHF handhelds should not be used ashore absent FCC or NTIA authorization allowing such use.

Outside the U.S.

Outside the U.S., users can obtain an MMSI assignment from their telecommunications authority or ship registry, often by obtaining or amending their ship station license. Canadians can obtain an MMSI from Industry Canada.

MMSI Format

Maritime Identification Digits (MID)

MIDs are three digit identifiers ranging from 201 to 775 denoting the administration (country) or geographical area of the administration responsible for the ship station so identified. See the ITU Table of Maritime Identification Digits.

Ships

All ship MMSIs use the format M₁I₂D₃X₄X₅X₆X₇X₈X₉ where in the first three digits represent the Maritime Identification Digits (MID) and X is any figure from 0 to 9.  (Hint: Ships transmitting with an MMSI not starting with the digits 201-775 are likely doing so improperly, and may be subject to FCC or USCG enforcement action)

Groups of Ships

Group ship station call identities for calling simultaneously more than one ship use the format 0₁M₂I₃D₄X₅X₆X₇X₈X₉ , where the first figure is zero and X is any figure from 0 to 9. The MID represents only the territory or geographical area of the administration assigning the group ship station call identity and does not prevent group calls to fleets containing more than one ship nationality.  

No process currently exists to assign non-federal group ship station identities.  However, users having an MMSI assigned by FCC license, all of which have a trailing zero, may create a group identity by inserting a zero before the identity and removing the trailing zero (e.g. a user having an MMSI of 366123450 is allowed to use the group identity 036612345). 

The U.S. Coast Guard group ship station call identity is 036699999.

Coast Radio Stations (Base Stations)

All coast or base stations use the format 0₁0₂M₃I₄D₅X₆X₇X₈X₉,where the digits 3, 4 and 5 represent the MID and X is any figure from 0 to 9.  Groups of coast radio stations use the same format.

The combination 0₁0₂M₃I₄D₅0₆0₇0₈0₉ is used to address all 00MIDXXXX stations within the administration.  The combination 0₁0₂9₃9₄9₅0₆0₇0₈0₉ is used to address all VHF 00XXXXXXX stations worldwide.  These two special combinations are not used in the United States.

The U.S. Coast Guard group coast station identity is 003669999.

Search and Rescue Aircraft

AIS and DSC equipment used on search and rescue aircraft use the format 1₁1₂1₃M₄I₅D₆X₇X₈X₉ where the digits 4, 5 and 6 represent the MID and X is any figure from 0 to 9. In the United States, these MMSIs are currently only used by the U.S. Coast Guard.

AIS Aids to Navigation (AtoN)

AIS used as an aid to navigation uses the format 9₁9₂M₃I₄D₅X₆X₇X₈X₉ where the digits 3, 4 and 5 represent the MID and X is any figure from 0 to 9. In the United States, these MMSIs are reserved for the federal government.

Craft Associated with a Parent Ship

AIS and DSC equipment used on craft associated with a parent ship, such as a launch, uses the format 9₁8₂M₃I₄D₅X₆X₇X₈X₉ where the digits 3, 4 and 5 represent the MID and X is any figure from 0 to 9.  No provision currently exists for using these identities in the United States. 

AIS Search and Rescue Transmitter (SART)

AIS search and rescue transmitters (SART) use the format 9₁7₂0₃X₄X₅Y₆Y₇Y₈Y₉, where the digits 4 and 5 are assigned by the International Association for Marine Electronics Companies (CIRM) and refer to the SART manufacturer, and digits 6, 7, 8 and 9 are sequential digits assigned by the manufacturer identifying the SART.

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