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21-613: An MMSI comprises a series of nine digits, consisting of three Maritime Identification Digits (country-codes), concatenated with a specific identifier. Whenever an object is re-flagged, a new MMSI must be assigned. A "maritime object" could be anything that requests an MMSI identifier.—e.g., a vessel, fixed offshore installation, mobile unit, maritime aircraft, coast station, etc. Communications may be routed to "individual objects", or to "groups of objects". A group call to objects can be based on an object's locale, owner/operator/fleet, type, etc. or combinations thereof. MMSI are formed in such

42-494: A ship station identity is formed as follows: where 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: If the ship is fitted with an Inmarsat C ship earth station, or it is expected to be so equipped in

63-463: A way that the identity or part thereof can be used by telephone and telex subscribers connected to the general telecommunications network to call any of these objects automatically. Communications are sent in digital form over a radio frequency channel. As of 2024, there are six kinds of maritime mobile service identities: An MID consists of three digits, always starting with a number from 2 to 7 (assigned regionally). A second MID can be assigned once

84-657: Is a conference organized by the ITU to review and, as necessary, revise the Radio Regulations , the international treaty governing the use of the radio-frequency spectrum as well as geostationary and non-geostationary satellite orbits. It is held every three to four years. Prior to 1993, it was called the World Administrative Radio Conference (WARC); in 1992, at an Additional Plenipotentiary Conference in Geneva ,

105-708: The Federal Communications Commission normally as part of the ship station license application 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 United States Coast Guard group ship station call identity is 036699999, and the group coast station call identity is 003669999. In the U.S., MMSIs are primarily used for digital selective calling and for assigning Inmarsat identities. 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

126-499: The 50 or 60 Hz current used in electrical power distribution . The radio spectrum of frequencies is divided into bands with conventional names designated by the International Telecommunication Union (ITU): Frequencies of 1 GHz and above are conventionally called microwave , while frequencies of 30 GHz and above are designated millimeter wave . More detailed band designations are given by

147-482: The MMSI can be used in such cases, and no longer need to end in trailing zeros. Radio frequency Radio frequency ( RF ) is the oscillation rate of an alternating electric current or voltage or of a magnetic , electric or electromagnetic field or mechanical system in the frequency range from around 20  kHz to around 300  GHz . This is roughly between the upper limit of audio frequencies and

168-1084: The body. That being said, there is limited studies on how effective these devices are. Test apparatus for radio frequencies can include standard instruments at the lower end of the range, but at higher frequencies, the test equipment becomes more specialized. While RF usually refers to electrical oscillations, mechanical RF systems are not uncommon: see mechanical filter and RF MEMS . ELF 3 Hz/100 Mm 30 Hz/10 Mm SLF 30 Hz/10 Mm 300 Hz/1 Mm ULF 300 Hz/1 Mm 3 kHz/100 km VLF 3 kHz/100 km 30 kHz/10 km LF 30 kHz/10 km 300 kHz/1 km MF 300 kHz/1 km 3 MHz/100 m HF 3 MHz/100 m 30 MHz/10 m VHF 30 MHz/10 m 300 MHz/1 m UHF 300 MHz/1 m 3 GHz/100 mm SHF 3 GHz/100 mm 30 GHz/10 mm EHF 30 GHz/10 mm 300 GHz/1 mm THF 300 GHz/1 mm 3 THz/0.1 mm World Radio Conference The World Radiocommunication Conference ( WRC )

189-460: 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 are formed as follows: 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 for calling simultaneously more than one coast station have

210-522: The current proliferation of radio frequency wireless telecommunications devices such as cellphones . Medical applications of radio frequency (RF) energy, in the form of electromagnetic waves ( radio waves ) or electrical currents, have existed for over 125 years, and now include diathermy , hyperthermy treatment of cancer, electrosurgery scalpels used to cut and cauterize in operations, and radiofrequency ablation . Magnetic resonance imaging (MRI) uses radio frequency fields to generate images of

231-454: The first or subsequently allocated MID 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 can be found in Table 1 of ITU Radio Regulations Appendix 43. The initial digits of an MMSI categorize the identity, as defined in by Recommendation M.585. The meaning of the first digit is: The 9-digit code constituting

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252-432: The foreseeable future, then the identity could have one trailing zero: 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 for calling simultaneously more than one ship are formed as follows: where the first figure is zero, and X is any figure from 0 to 9. The particular MID represents only

273-521: 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

294-413: The human body. Radio Frequency or RF energy is also being used in devices that are being advertised for weight loss and fat removal. The possible effects RF might have on the body and whether RF can lead to fat reduction needs further study. Currently, there are devices such as trusculpt ID , Venus Bliss and many others utilizing this type of energy alongside heat to target fat pockets in certain areas of

315-544: 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

336-544: The lower limit of infrared frequencies, and also encompasses the microwave range. These are the frequencies at which energy from an oscillating current can radiate off a conductor into space as radio waves , so they are used in radio technology, among other uses. Different sources specify different upper and lower bounds for the frequency range. Electric currents that oscillate at radio frequencies ( RF currents ) have special properties not shared by direct current or lower audio frequency alternating current , such as

357-819: The manufacturer, rather than a country's MID: The digitals represented by the two Y characters are assigned by the International Association for Marine Electronics Companies and refer to the SART manufacturer, while the Xs are sequential digits assigned by the manufacturer identifying the SART. In the United States (one of whose MIDs is 366), 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

378-506: The radio from one boat to another. This is especially egregious for hand-held VHF devices, for which a single MMSI number makes little sense. 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

399-502: The same format as individual coast station IDs: two leading zeros, the MID, and the four digits. They are formed as a subset of coast station identities, as follows: US Coast Guard stations use a non-standard MMSI: 003669999 - any US Coast Guard Base station Note that administrations in other countries may use different formats. Reference: ITU-R Recommendations M.585-7 AIS Search and Rescue Transmitters ( AIS-SART ) have an identifier related to

420-411: 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. To help mitigate against MMSI number exhaustion, manufacturers are required to cripple DSC-capable radios so that an MMSI number can only be entered once, which means that a device owner may not move

441-465: The standard IEEE letter- band frequency designations and the EU/NATO frequency designations. Radio frequencies are used in communication devices such as transmitters , receivers , computers , televisions , and mobile phones , to name a few. Radio frequencies are also applied in carrier current systems including telephony and control circuits. The MOS integrated circuit is the technology behind

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