MARITIME
MOBILE SERVICE IDENTITY
The International Telecommunications Union
The International
Telecommunications Union in Geneva, Switzerland, oversees
the use and assignment of maritime mobile service identities.
The information contained here is incomplete, adapted from
regulations and recommendations of the ITU, and practices
within the United States. For complete information, we recommend
you obtain the relevant information directly from the ITU.
Maritime Mobile Service Identities
Please see guidance to administrations
for the assignment and conservation of maritime mobile service
identities (MMSI).
(Adapted from Appendix 43 of the International Telecommunications
Union Radio Regulations)
Maritime Mobile Service Identities are formed of a series
of nine digits which are transmitted over the radio path in
order to uniquely identify ship stations, ship earth stations,
coast stations, coast earth stations, and group calls. These
identities are formed in such a way that the identity or part
thereof can be used by telephone and telex subscribers connected
to the general telecommunications network principally to call
ships automatically.
There are four kinds of maritime mobile service identities:
- Ship station identities,
- Group ship station identities,
- Coast station identities,
- Group coast station identities.
The First Digit of an MMSI
The first digit or two of an MMSI means something, and from
it you can tell something about the identity:
First digit(s) Meaning
0X Ship Group identity Coast station, or Group of Coast Stations
1 Not used (the seven digit identity beginning with "1"
is used by Inmarsat A)
2 These are valid MMSI's used by individual ships
. "
. "
7 "
8 Assigned for Regional Use
9 Assigned for National Use
Maritime Identification Digits (MID)
A single MID has been allocated to each country. A second
MID can be assigned once the MID first or subsequently allocated
is more than 80% exhausted and the rate of assignments is
such that 90% exhaustion is foreseen. A listing of MIDs assigned
to each country is provided in table 1 to Appendix 43 of the
ITU Radio Regulations.
A MID always starts with a digit from 2 to 7.
Ship Station Identities
The 9-digit code constituting a ship station identity is
formed as follows:
MIDXXXXXX
wherein MID represent the Maritime Identification Digits
and X is any figure from 0 to 9.
If the ship is fitted with an Inmarsat B, C or M ship
earth station, or it is expected to be so equipped in the
foreseeable future, then the identity should have three trailing
zeros:
MIDXXX000
If the ship is fitted with an Inmarsat C ship earth
station, or it is expected to be so equipped in the foreseeable
future, then the identity could have one trailing zeros:
MIDXXXXX0
If the ship is fitted with an Inmarsat A ship earth
station, or has satellite equipment other than Inmarsat, then
the identity needs no trailing zero.
Group Ship Station Call Identities
Group ship station call identities for calling simultaneously
more than one ship are formed as follows:
0MIDXXXXX
where the first figure is zero and X is any figure from 0
to 9. The particular MID represents only the country assigning
the group ship station call identity and so does not prevent
group calls to fleets containing more than one ship nationality.
Coast Station Identities
Coast station identities are formed as follows:
00MIDXXXX
where the first two figures are zeros and X is any figure
from 0 to 9. The MID reflects the country in which the coast
station or coast earth station is located.
Group Coast Station Call Identities
Group coast station call identities for calling simultaneously
more than one coast station are formed as a subset of coast
station identities, as follows:
00MIDXXXX
where the first two figures are zeros and X is any figure
from 0 to 9.
In the United States
In the U.S., federal MMSIs are assigned by the National Telecommunications
and Information Administration, and are normally, but not
always, formed as 3669XXXXX. Non federal MMSIs are assigned
by the Federal Communications Commission normally as part
of the ship station license application (Form 506), and are
formed as 366XXX000 for ships on international voyages and
ships needing an Inmarsat mobile earth station, or 366XXXXX0
for all other ships.
The U.S. Coast Guard group ship station call identity is
036699999, and group coast station call identity is 003669999.
In the U.S., MMSIs are primarily used for digital selective
calling and for assigning Inmarsat identities. For more information,
see Maritime Distress & Safety Telecommunication
Data Elements
Assignment of Ship Station Identification
(adapted from ITU-R Recommendation M.585-2)
Restrictions may apply with respect to the maximum number
of digits which can be transmitted on some national telex
and/or telephone networks for the purpose of ship station
identification. At present, the maximum number of digits that
are transmitted that are able to be transmitted over the national
networks of many countries for the purpose of determining
ship station identity is six. The digits carried on the network
to represent the ship station identity is referred to as the
"ship station number" in this text and in the relevant
ITU-T Recommendation. The use of the techniques described
below should make it possible for the coast stations of such
countries to engage in the automatic connection of calls to
ship stations.
To obtain the required nine-digit ship station identity a
series of trailing zeros is added to the ship station number
by the coast station for shore-originated automatic services,
e.g.:
Ship station number Ship station identity
MIDXXX MIDXXX000
As long as the restrictions above apply in one's own network
limiting ship station numbers to 6 digits, ships that intend
to receive automatic network traffic from national coast stations
only, should be assigned identities wherein X(9),
but not X(8), =0. This assumes that "9"
is used to abbreviate the national MID for such ships for
network purposes.
Ship station number Ship station identity
9XXXXX MIDXXXXX0
As long as the restrictions above apply it may be useful
for some administrations to expand the capacity for numerical
ship station identification by using as many as ten"8Y"
abbreviations for MIDs. Such a technique may allow the assignment
of ship station identities wherein trailing zeros are applied
only to X(8) and X(9).
Ship station number Ship station identity
8YXXXX MIDXXXX00
The usefulness of this technique to a given administration
may depend on whether its abbreviation (e.g. 83) of its own
MID is duplicated in other administrations in which some of
its ships have a community of interest. When such is the case
the ship in question can be called using the same ship station
number in all the automatic networks of interest to that ship.
As an example, a group of up to ten countries, with community
of interest, might agree to assign the same abbreviation for
their respective MIDs. The abbreviation should always relate
to the numerically lowest MID, when more than one is assigned
to a given country.
Country "8Y" Assignment
A 80
B 81
C 82
D 83
E 84
F 85
G 86
H 87
I 88
J 89
All countries recognize a particular 8Y abbreviation as associated
with a particular country. For example a coast station in
any of the countries A-J receiving "83"as the first
two digits of a ship station number would transmit the MID
of the country D.
As long as the restrictions described above apply, ships
that reply regular automatic communications from foreign coast
stations additional to those that may conform to the abbreviation
arrangements above shall only be assigned ship station identities
with X(7)X(8)X(9) = 000 to
support 6 digit ship station numbers.
When it becomes necessary to progress to stage 2, (seven
digit ship station numbers for automatic shore-originated
traffic) in the ship station identity scheme the format of
ship station identities described in the previous paragraph
would change from MIDXXX000 to MIDXXXX00. If "8Y"
abbreviations are used in stage 1 (six digit ship station
numbers for automatic shore-originated traffic) some ship
station identity assignments will already have taken the MIDXXXX00
format. It would therefore be useful to reserve at least one
value in the X(7) digit position if ship station
identity assignments are made on the basis of "8Y"
network abbreviations:
Ship station number Ship station identity
8YXXXX MIDXXXX00
Assignment of Identification to Aircraft
When an aircraft is required to use maritime mobile service
identities for the purposes of conducting search and rescue
communications with stations in the maritime mobile service,
the responsible administration should assign a nine-digit
unique aircraft identity, in the format 111213M4I5D6X7X8X9
where the digits 4, 5 and 6 represent the MID and X is any
figure from 0 to 9. The MID represents only the territory
or geographical area of the administration assigning the aircraft
call identity.
The administration may use the seventh digit to differentiate
between certain specific uses of this class of MMSI, as shown
in the example applications below:
a) 111MID1XX Fixed-wing aircraft
b) 111MID5XX Helicopters
The combination 111213M4I5D6070809 should be reserved for
a Group Aircraft Identity and should address all 111MIDXXX
stations within the administration. The administration may
further augment this with additional Group Call identities,
i.e. 111MID111, etc.
Assignment of Identification to AIS Aids to Navigation (AtoN)
When a means of automatic identification is required for
a station aiding navigation at sea, the responsible administration
should assign a nine-digit unique number in the format 9192M3I4D5X6X7X8X9
where the digits 3, 4 and 5 represent the MID and X is any
figure from 0 to 9. The MID represents only the territory
or geographical area of the administration assigning the call
identity for the navigational aid.
The format shown above applies to unmanned AIS AtoN floating
in the water and virtual AIS AtoN belonging to aids to navigation
systems; however, aids to navigation systems mounted ashore
on fixed land or on an island should be assigned an identification
number in the format given in Annex 2.
The administration may use the sixth digit to differentiate
between certain specific uses of the MMSI, as shown in the
example applications below:
a) 99MID1XXX Physical AIS AtoN
b) 99MID6XXX Virtual AIS AtoN
Assignment of Identification to Craft Associated with a
Parent Ship
Devices used on craft associated with a parent ship, need
unique identification. These devices which participate in
the maritime mobile service should be assigned a nine-digit
unique number in the format 9182M3I4D5X6X7X8X9 where the digits
3, 4 and 5 represent the MID and X is any figure from 0 to
9. The MID represents only the territory or geographical area
of the administration assigning the call identity for the
craft associated with a parent ship.
This numbering format is only valid for devices on board
crafts associated with a parent ship. A craft may carry multiple
devices for which a MMSI is required. These devices may be
located in lifeboats, life-rafts, MOB-boats or other craft
belonging to a parent ship.
A unique MMSI should be assigned for each device onboard
a craft associated with a parent ship and will have to be
separately registered and linked to the MMSI of the parent
ship.
The Exhaustion of MMSIs
Because all ships on international voyages, as well as all
ships fitted with an Inmarsat B or M ship earth station, are
assigned MMSIs of the format MIDXXX000, a serious problem
has arisen internationally in assigning sufficient numbers
of MIDs to all administrations that need them. For example,
a country having 10,000 Inmarsat-equipped ships would require
10 MIDs just to accommodate those 10,000 ships. If 50,000
boaters decided to fit small Inmarsat M terminals, 50 additional
MIDs would be required to accommodate them.
The problem exists with Inmarsat-equipped ships because ITU-T
recommendations require that Inmarsat ship earth stations
be assigned the identity (MESIN) TMIDXXXYY, where T indicates
the type of Inmarsat station, YY indicates the Inmarsat station
extension (e.g."00" might indicate a telephone in
the bridge, "01" might indicate a fax machine in
the radio room, etc), and MIDXXX indicates the ship station
number, which relates to the assigned ship station identity
MIDXXX000.
The MMSI was meant to be an all-inclusive ship electronic
identity, used in one form or another by every GMDSS or telecommunications
instrument on the ship. Questions have been raised, however,
whether the MMSI can in practice totally fulfill that role.
ITU may eventually end the practice of relating Inmarsat MESIN
identities with the ship MMSI identity.
The World radio Conference, Geneva, 1997 (WRC-97), adopted
Resolution 344 concerning the exhaustion of the maritime mobile
service identity resource. In view of improvements to public
switched telephone networks, and new capabilities of the Inmarsat
system other than Inmarsat B or M, previous restrictions should
no longer be applicable. All nine digits of the MMSI can be
used in such cases, and no longer need to end in trailing
zeros.
How To Obtain an MMSI Assignment
U.S. Non-Federal User
Commercial users, or those who travel outside the U.S. or
Canada, must apply for a ship station
license, or an amendment to a ship station license, to
obtain an MMSI.
Non-commercial users (e.g. recreational boaters) who stay
in U.S. waters can obtain an MMSI through BOAT
US and SeaTow.
U.S. Federal User
Federal users can obtain MMSI assignments from their agency
Interdepartment Radio Advisory Committee (IRAC) representatives.
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.
International Telecomms Union Maritime Mobile Access Retrieval
System
You can access
the list of Maritime Identification Digits assigned to
each country, or look up information concerning a vessel using
its MMSI or radio call sign from the Telecommunications Union
Maritime Mobile Access Retrieval System.
For More Information...
The following are ITU publications dealing with forming and
assigning of MMSIs and the usage of MIDs:
Forming and assigning of MMSIs:
- Rec ITU-R M.585-2 (Assignment and Use of MMSIs) 1994
- Rec ITU-T E.210/F.120 (Ship Station Identification of
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