DSC Handheld VHF Question

[Day Dreams]

When you are adding a new VHF handheld with DSC do you apply for a new MMSI number? Or do you use your boats fixed VHF MMSI number? Can't find complete clarity on this.

Thanks,

[vaporware]

In the U.S., Boat US says either. If you are a Boat US member, MMSI numbers are free from them, but the numbers are not valid outside the U.S. If you are in the U.S and plan to use the handheld on more than one boat, I would get a separate Boat US number as you can change the information online. If you are not in the U.S. or have an FCC MMSI, things are different.



See the Boat US MMSI site for more information.

[continuouswave]

Originally Posted by Day Dreams

When you are adding a new VHF handheld with DSC do you apply for a new MMSI number? Or do you use your boat[']s fixed VHF MMSI number?

The maritime mobile service identity (MMSI) is most often assigned to a vessel, that is, to a ship station. A maritime communication call routing radio system uses this identity to specify the recipient or sender of a radio transmission. The MMSI is used for all devices on a vessel using those services that employ the MMSI method.

Digital Selective Calling is one of the services that uses the MMSI identifier. All the DSC radios on a vessel should use the same MMSI, including handheld radios. In general, the MMSI is not associated with a particular individual radio device on the vessel.

The only situation in which a handheld DSC radio should use an MMSI that is DIFFERENT from the vessel's MMSI is if the handheld radio is NOT associated with one particular vessel. Such a radio could be a diver's radio, and the diver does not own a vessel.

In the scheme for assignment of MMSI numbers, there is a unique numbering format for such handheld DSC radios to be used "for special purposes." One of the reasons for having a unique MMSI number format for handheld radios is to denote the radio as handheld and thus likely battery powered, suggesting limited power and limited operating time, so that rescuers can be aware of those limitations.

If you own a handheld DSC radio and do not own a vessel, or if you intend to use the handheld radio on many vessels, then the handheld DSC radio should get its own MMSI with the MMSI number in accordance with the "for special purposes" scheme for such radios.

In the USA there is a problem in complying with these recommendations: there is no MMSI-issuing agency that can provide an MMSI in the recommended unique-to-handheld-radio "for special purposes" format.

In the USA, the recommendation is then to use an MMSI from a non-governmental issuing agency, such as BoatUS or the U.S. Power Squadron to a handheld radio that is "for special purposes."

Originally Posted by Day Dreams

Can't find complete clarity on this.

I hope my remarks give you some clarity. If you want further reading, I recommend you read the ITU Recommendation on MMSI. The applicable document is

RECOMMENDATION ITU-R M.585-8
Assignment and use of maritime mobile service identities
(10/2019)

You can obtain this document at no cost by on-line access to a PDF version. Here is the link to the English language version:

https://www.itu.int/dms_pubrec/itu-r...0-I!!PDF-E.pdf

Please read at ANNEX 2 SECTION 1, at sub-heading
"Assignment of identities for handheld VHF transceivers with digital selective calling and global navigation satellite system"

You can also find advice about MMSI use in the USA from the U.S Coast Guard NAVCEN website. The link is

https://www.navcen.uscg.gov/?pageName=mtmmsi

[continuouswave]

Originally Posted by vaporware

...If you are a Boat US member, MMSI numbers are free from them, but the numbers are not valid outside the U.S.

I don't know exactly what is to be inferred from the description "not valid."

An MMSI provided by BoatUS will work anywhere on the globe and will interoperate with any other DSC radio in any location.

The only limitation of an MMSI number issued by BoatUS (or by other "licensed-by-rule" MMSI providers in the USA) is those identities will not be forwarded to other countries for identification of vessel owner and other details of the vessel.

Boaters in the USA are governed by the regulations of the Federal Communications Commision with regard to use of VHF Marine Band radios in foreign waters and in communication with foreign shore stations, and those regulations require USA boats that visit foreign ports and communicate with foreign shore stations to have an FCC-issued SHIP STATION LICENSE, and (at the least) an FCC Marine Radio OPERATOR'S PERMIT, and as such would use an MMSI issued by the FCC. MMSI obtained from the FCC are communicated to an international data base and should be available to rescue authorities on a global basis.

The ITU SHIP STATION LIST is available for searching on-line by MMSI identity. See:

https://www.itu.int/mmsapp/ShipStation/list

An FCC-issued MMSI should be easily found in the list, although there have been some occasional omissions.

The scheme used in the USA for assignment of MMSI numbers is somewhat unique. FCC-issued MMSI numbers will always end in a zero. Licensed-by-rule-issued MMSI numbers from non-FCC registering agencies will end in digits 1 to 9.

For advice on when an FCC SHIP STATION LICENSE is needed, see

https://www.fcc.gov/bureau-divisions...ions#licensing