Three of the nine digits of an MMSI identify country of origin. In the case of a coast station these digits indicate the country of location, and in the case of a ship station, the country of registration. The remaining six digits uniquely identify the station itself. The three digits identifying the country are known as the maritime identification digits or MID. Australia's MID is 503.
An Australian vessel MMSI takes the form 503xxxxxxwhere x is any figure from 0 to 9.
An Australian coast station MMSI takes the form 00503xxxx where the first two figures are zero and x is any figure 0 to 9.
A full international list of MIDs appears in list VIIA, list of callsigns and numerical identities published by the International Telecommunication Union (ITU), the ITU Manual for use by the Maritime Mobile and Maritime Mobile-Satellite Services and the Australian Global Maritime Distress and Safety System (GMDSS) Handbook.
Groups of vessels can be called via DSC by a group ID or group MMSI. Group MMSIs are finding use by fleets and yacht races. Safety and urgency DSC calls (Announcements) can be sent to a group MMSI. Each vessel desiring to be part of a group would enter the same group MMSI into their DSC equipment, which usually can be named for convenience by the user.
Group MMSI numbers begin with a single 0 before the MID, so it takes the form 0503xxxxx (where x is any figure from 0 to 9).
Group MMSIs can be manually programmed into a DSC-equipped transceiver by the user at will (unlike the self-ID). Any number with a leading zero can be used as a group MMSI, and they do not need to be registered, but the entity deciding on a group MMSI must use the MID of the host country or country of vessel registration.
The group ID should be based on a key vessel in the group, and a good way to proceed is to drop the last digit of the lead vessel’s MMSI and place a zero in front of the 503 as follows:
Example 1: a fleet of vessels has a lead or main vessel with a DSC self-ID of 503123456 and wishes to set up a group MMSI for a special event. The group ID could be 050312345.
This would then be programmed into all fleet vessels as the special event group MMSI.
Example 2: a fleet of vessels has a lead or main vessel with a DSC self-ID of 503080110. The group MMSI could be 050308011. This would then be programmed into all fleet vessels as the special event group MMSI.
Group MMSI numbers are not to be used for AIS transceivers.
Maritime identities for handheld portable VHF DSC transceivers
We recognise the safety potential of VHF marine transceivers with DSC capability. Our policy for these units are to allocate MMSIs to individual radio transceivers rather than to a single vessel-specific MMSI. In Australia, until January 2012, these transceivers' maritime identities had the format 5039xxxxx where x is any figure from 0 to 9.
From January 2012, Australian handheld VHF transceivers with DSC now use the maritime identity format 8503xxxxx, where x is any figure from 0 to 9, in accordance with recommendation ITU-R M.585-6, annex II, section I.
When a handheld VHF transceiver with DSC changes ownership, we need to be advised of the new owner's details.
Handheld VHF transceivers with DSC are issued to persons, rather than vessels, in recognition that these transceivers can move between vessels.
The requirement to present a copy of an appropriate radio operator's qualification when applying for an MMSI also applies to MMSIs requested for the portable VHF DSC transceivers.
Diver handheld VHF DSC transceivers
Effective as from November 2013, the Australian Communications and Media Authority does not mandate a marine radio operator certificate prior to the issuing of an MMSI for personally attached diver VHF radios, that offer a digital selective calling transmit capability, and limited voice communications. This presumes that the radio operator in the diving boat (mother vessel) is qualified. In the case of lone divers not operating from boats, the requirement for a marine radio operator certificate remains.
MOB / MSLS devices using VHF DSC channel 70
Maritime survivor locating systems or man overboard devices compliant with AS/NZS 4869.4 may use distress alerts via DSC using VHF DSC channel 70. In Australia, you can use automated voice announcements indicating distress using the man overboard indication on the distress, urgency and safety and calling frequency of 156.8 MHz (VHF channel 16).
Such low-power devices also may indicate the position of the man overboard distress in the DSC message and/or in Australia, the voice message. Such announcements have distress priority and are to be treated as distress transmissions. Stations receiving these alerts should be aware that these alerts and messages are one-way broadcast messages to all stations in range, and cannot be acknowledged of cancelled until the battery is exhausted or sinks.
Some of these devices, developed for overseas markets, contain a DSC receiver, which allows acknowledgment or cancellation by a coast station or SOLAS vessel (but only under direction of a coast station or the JRCC as per IMO COMSAR/Circ.25).
The intention of these devices is to enable vessels and coast stations in range to facilitate rescue of persons in distress in the shortest possible time.
MOB/MSLS devices using automatic Iientification system frequencies
A number of devices used as man overboard devices (maritime survivor locating systems or devices) use AIS technology based on the on burst transmissions defined in annex 9 of recommendation ITU-R M.1371. Early versions of these devices have the maritime identity of the format 970xxyyyy, but newer units starting from 2011, use the format 972xxyyyy1, which has been internationally agreed in recommendation ITU-R M.585-6, annex 2, section 2.
There is currently no AS/NZS standard for these devices, but they should be certified by a competent testing house that they are sufficiently compliant with the IEC 61097-14 for the purpose it is intended, or fully compliant with overseas standards, such as RTCM 11901.1 (June 2012). Additional overseas standards for these devices are under development.
1 Maritime survivor locating systems (AS/NZS 4869.4) until January 2012 used the maritime identity in the format 5038XXXXX. These systems now use the internationally agreed format 972xxyyyy, where x and y are any numbers between 0 and 9. The number is pre-programmed. The xx numbers are allocated to manufacturers by the International Association for Marine Electronics Companies (CIRM), and the yyyy numbers are allocated by the manufacturer as sequential numbers. In accordance with recommendation ITU-R M.585-6, the sequential numbers can be re-used once 9999 is reached. AMSA does not allocate these numbers, and no radio operator licence is required.