# Can a ship change its MMSI NUMBER ?



## wbmkk (Jun 11, 2008)

Can a ship change its MMSI number?

Today I saw a small container ship, the Oeland leave the post of Tyne (Newcastle) on the way to Rotterdam.

I see on several shipping websites that the IMO number is 9277400, but as far as the MMSI number some sites show it as 256639000 while others say it is 255806008

Which one is correct please ?

thank you


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## Wismajorvik (Dec 29, 2011)

wbmkk said:


> Can a ship change its MMSI number?
> 
> Today I saw a small container ship, the Oeland leave the post of Tyne (Newcastle) on the way to Rotterdam.
> 
> ...


Only one MMSI at a time. Possibly vessel changed from Maltese registration to Portuguese at some time.


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## Ron Stringer (Mar 15, 2005)

The IMO (International Maritime Organisation - an agency of the UN) number is a unique identity assigned to the ship at construction and retained for life, regardless of the ship's name or country of registry.

An MMSI number is the maritime equivalent of a telephone number. MMSI numbers are assigned in blocks, to each country by the ITU (International Telecommunications Union) and then individual numbers from within its assigned block are issued by a country to each ship that registers with that country. When a ship switches registration it must be assigned a new MMSI number by the new country of registry.


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## Dickyboy (May 18, 2009)

Ron Stringer said:


> The IMO (International Maritime Organisation - an agency of the UN) number is a unique identity assigned to the ship at construction and retained for life, regardless of the ship's name or country of registry.
> 
> An MMSI number is the maritime equivalent of a telephone number. MMSI numbers are assigned in blocks, to each country by the ITU (International Telecommunications Union) and then individual numbers from within its assigned block are issued by a country to each ship that registers with that country. When a ship switches registration it must be assigned a new MMSI number by the new country of registry.


(Thumb)(Thumb)


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## wbmkk (Jun 11, 2008)

Wismajorvik said:


> Only one MMSI at a time. Possibly vessel changed from Maltese registration to Portuguese at some time.


Many thanks for the answer


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## wbmkk (Jun 11, 2008)

Ron Stringer said:


> The IMO (International Maritime Organisation - an agency of the UN) number is a unique identity assigned to the ship at construction and retained for life, regardless of the ship's name or country of registry.
> 
> An MMSI number is the maritime equivalent of a telephone number. MMSI numbers are assigned in blocks, to each country by the ITU (International Telecommunications Union) and then individual numbers from within its assigned block are issued by a country to each ship that registers with that country. When a ship switches registration it must be assigned a new MMSI number by the new country of registry.


Cheers Ron !


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## OzBoz (Dec 9, 2008)

"...a unique identity assigned to the ship at construction and retained for life, regardless of the ship's name or country of registry."

"When a ship switches registration it must be assigned a new MMSI number by the new country of registry."

Sorry Ron, now I'm confused.

Brian


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## Bob McManamon (Oct 15, 2011)

*The answer is Yes and No*

A DSC unit can be programmed with up to 4 different MMSI numbers, e.g. for a company (fleet) MMSI number, or ships with a common interest such as nationality or whatever. These are called Group MMSI numbers. But there should never be two ship-identifying MMSI numbers. This would cause confusion in a SAR situation to say the least. If a DSC unit is transferred to a different ship, the MMSI number must be changed otherwise RCC would be looking for the wrong ship. In this case, MID 255 is for Portugal and 256 is for Malta. To find out which one is correct, you would need to approach the administrations of those two countries. Or perhaps look up the ITU List of Call Signs and Numerical Identities, although this itself can only be updated after the flag states have informed the ITU. A ship’s IMO number is welded into the ship and never changes throughout its life, no matter how many times it is sold or renamed. The MMSI can be changed many times but there should only be one number at a time. In the first few iterations of DSC Specifications (of which there have been about 15 altogether, patching up oversights and other problems), such as those applying to the Sailor 2000 series, it was easy to change the MMSI number: remove the bottom panel, flip a switch, key in the number and flip the switch back again. The IMO subsequently changed the specifications so that it was not so easy for the owner/operator to change the number. It had to be done by entering a code group which was supposed to be known only to authorised service technicians. That’s why the answer is Yes and No! Yes a ship could have two numbers, but No it shouldn’t. A quirk of the original Sailor 2000 series was that the instructions in the Installation Manual, if the ship had no Group MMSI numbers, were that the digits 000000000 were to be entered in the three extra MMSI slots. What happened in practice was that every DSC call addressed to MMSI 000000000 would activate every Sailor 2000 DSC within range. This happened to me on many occasions and I was completely at a loss to understand why we were receiving so many calls from strange vessels of many flag states, usually containing absolutely ridiculous Telecommands. It wasn’t until I started teaching that I came across an Installation Manual and noticed the 000000000 instruction (and learnt how the MMSI could be so easily changed). The penny finally dropped! The senders had evidently been testing or practicing on their DSCs and addressing them to 000000000, thinking that this would not activate other vessels. Incidentally, the three trailing zeros usually means that the ship is fitted with an Inmarsat mobile earth station.(Whaaa)


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## Ron Stringer (Mar 15, 2005)

OzBoz said:


> Sorry Ron, now I'm confused.


Sorry to hear that Brian.


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## Orbitaman (Oct 5, 2007)

OzBoz said:


> "...a unique identity assigned to the ship at construction and retained for life, regardless of the ship's name or country of registry."
> 
> "When a ship switches registration it must be assigned a new MMSI number by the new country of registry."
> 
> ...


Brian,
In simple terms:
IMO number stays with the ship throughout its life, regardless of changes of names, nationality, etc
MMSI number can be changed as required, whether its change of name, ownership, flag, etc.
It should be remembered that an MMSI number is basically a digital call sign and has nothing to do with the IMO number.
By the way, the IMO number also has nothing to do with a vessel's Official number


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