Code letters or ship's call sign (or callsign) [1] [2] were a method of identifying ships before the introduction of modern navigation aids and today also. Later, with the introduction of radio, code letters were also used as radio call signs.
Code letters or ship's call sign (or callsign) [1] [2] were a method of identifying ships before the introduction of modern navigation aids and today also. Later, with the introduction of radio, code letters were also used as radio call signs.
In 1857, the United Kingdom sponsored the Commercial Code of Signals for the Use of All Nations at Sea, which introduced four letter flag signal codes to identify individual ships. [3] The first vessel to be reported in Lloyd's List by her letters was the Mallard (LDPN), off Deal, Kent whilst on a voyage from London to Calcutta, India. [4] The Commercial Code of Signals, c. 1900, was modified to become the International Code of Signals. By the 1860s, individual ships were being allocated code letters in the United States and Europe. From 1874, code letters were recorded in Lloyd's Register as part of each individual vessel's entry in the register. Generally, code letters allocated to a ship remained with that ship, although there are known cases where new code letters have been allocated following a change of port of registry or owner. Code Letters were sometimes reallocated once a ship had been struck from the register, but no two ships bore the same code letters at the same time. [3] With the introduction of radio for communications, code letters were used also as radio call signs. [5]
Code letters used the twenty-six flags that represent the letters of the alphabet, plus the ten flags that represent the digits 0 - 9 also have been used. [1] The substitute flags have not been used for call signs.
Each flag has own name. If the ship's call sign is "3EJH2" 
(Panama Flag) [1] the seamen never say "Three E J H Two". They say "Three Echo Juliet Hotel Two" to avoid misunderstanding as every country seamen have own pronunciation of letters and during speech over radio letters can be inaudible.
If call sign has 4 characters, the first character or figure of ship's call signs means country code for the ships registered under this country flag. If call sign has 5 characters, the first two characters or figure plus character of ship's call signs means country code for the ships registered under this country flag. The variations 4 or 5 characters due to 36 characters (26 letters + 10 digits) are not enough for all countries. For or the Soviet Union was used character "U" as the first character in call signs: cargo ship Metallurg Anosov had call sign "USMW" 
. In case that the ship changes the flag she has to change call sign also. For example, the ship Heinrich Arp: Code Letters "RDWL" (1923-34) 
were changed to Code Letters "DHKV" (1934-45) 
and from 1946 once more to the Soviet Union Ship's call sign (unknown, but first character was "U").
If the ship is scrapped or sunk, usually after a long time her call sign can be given to another ship.
The last three characters of ship's call sign usually mean nothing, but one of them used as a code of the government Shipping Companies if the country has more than one Shipping companies.
Today, each sea-going ship must keep on board the book or computer's play-disk "List of Ship Stations and Maritime Mobile Service Identity Assignments" of ITU publication, fresh edition, where listed all sea-going ships and their call signs also. This book must be fresh due to renewal (new edition had place every some years). in this book (or disk) mentioned: "Call sign formed from the international call sign series in accordance with Article 19, Section III of the Radio Regulations (RR). The sign = (equal) in this column indicates that the name of the ship is used to identify the station in radiotelephony." [6] [7]
Some canals or narrow places have special requirements for the vessels to hoist their call sign flags during the transit through the area. The Suez Canal was once such place where this requirement was made. Thanks to technological advances in the navigation abilities of marine craft, this action is no longer compulsory.
A country code is a short alphanumeric identification code for countries and dependent areas. Its primary use is in data processing and communications. Several identification systems have been developed.
The International Telecommunication Union (ITU) allocates call sign prefixes for radio and television stations of all types. They also form the basis for, but may not exactly match, aircraft registration identifiers. These prefixes are agreed upon internationally, and are a form of country code. A call sign can be any number of letters and numerals but each country must only use call signs that begin with the characters allocated for use in that country.
Morse code is a method used in telecommunication to encode text characters as standardized sequences of two different signal durations, called dots and dashes, or dits and dahs. Morse code is named after Samuel Morse, one of the inventors of the telegraph.
The Q-code is a standardised collection of three-letter codes that each start with the letter "Q". It is an operating signal initially developed for commercial radiotelegraph communication and later adopted by other radio services, especially amateur radio. To distinguish the use of a Q-code transmitted as a question from the same Q-code transmitted as a statement, operators either prefixed it with the military network question marker "INT" or suffixed it with the standard Morse question mark UD.
SOS is a Morse code distress signal, used internationally, that was originally established for maritime use. In formal notation SOS is written with an overscore line, to indicate that the Morse code equivalents for the individual letters of "SOS" are transmitted as an unbroken sequence of three dots / three dashes / three dots, with no spaces between the letters. In International Morse Code three dots form the letter "S" and three dashes make the letter "O", so "S O S" became a common way to remember the order of the dots and dashes.
Marine VHF radio is a worldwide system of two way radio transceivers on ships and watercraft used for bidirectional voice communication from ship-to-ship, ship-to-shore, and in certain circumstances ship-to-aircraft. It uses FM channels in the very high frequency (VHF) radio band in the frequency range between 156 and 174 MHz, inclusive, designated by the International Telecommunication Union as the VHF maritime mobile band. In some countries additional channels are used, such as the L and F channels for leisure and fishing vessels in the Nordic countries. Transmitter power is limited to 25 watts, giving them a range of about 100 kilometres.
From early in the 20th century, the radio frequency of 500 kilohertz (500 kHz) was an international calling and distress frequency for Morse code maritime communication. For much of its early history, this frequency was referred to by its equivalent wavelength, 600 meters, or, using the earlier frequency unit name, 500 kilocycles or 500 kc.
A Maritime Mobile Service Identity (MMSI) is effectively a maritime object's international maritime telephone number, a temporarily assigned UID, issued by that object's current flag state.
An aircraft registration is a code unique to a single aircraft, required by international convention to be marked on the exterior of every civil aircraft. The registration indicates the aircraft's country of registration, and functions much like an automobile license plate or a ship registration. This code must also appear in its Certificate of Registration, issued by the relevant civil aviation authority (CAA). An aircraft can only have one registration, in one jurisdiction, though it is changeable over the life of the aircraft.
The International Code of Signals (INTERCO) is an international system of signals and codes for use by vessels to communicate important messages regarding safety of navigation and related matters. Signals can be sent by flaghoist, signal lamp ("blinker"), flag semaphore, radiotelegraphy, and radiotelephony. The International Code is the most recent evolution of a wide variety of maritime flag signalling systems.
In broadcasting and radio communications, a call sign is a unique identifier for a transmitter station. A call sign can be formally assigned by a government agency, informally adopted by individuals or organizations, or even cryptographically encoded to disguise a station's identity.
This is a list of airline codes. The table lists IATA's two-character airline designators, ICAO's three-character airline designators and the airline call signs. Historical assignments are also included.
Call signs in New Zealand are no longer generally used to identify broadcast stations. However, New Zealand's radio stations were once known by their call signs and would usually broadcast their call signs as a number followed by X, Y, or Z, and another letter. Call signs are regulated internationally by the ITU and nationally by the Ministry of Business, Innovation and Employment (MBIE), formerly the Ministry of Economic Development. The ministry is also responsible for providing policy advice to Government on the allocation of New Zealand's radio spectrum to support, efficient, reliable and responsive wireless telecommunications and broadcasting infrastructure.
The IMO number of the International Maritime Organization is a generic term covering two distinct meanings. The IMO ship identification number is a unique ship identifier; the IMO company and registered owner identification number is used to identify uniquely each company and/or registered owner managing ships of at least 100 gross tons (gt). The schemes are managed in parallel, but IMO company/owner numbers may also be obtained by managers of vessels not having IMO ship numbers. IMO numbers were introduced to improve maritime safety and reduce fraud and pollution, under the International Convention for the Safety of Life at Sea (SOLAS).
A telephone number is a sequence of digits assigned to a landline telephone subscriber station connected to a telephone line or to a wireless electronic telephony device, such as a radio telephone or a mobile telephone, or to other devices for data transmission via the public switched telephone network (PSTN) or other public and private networks.
Amateur radio call signs are allocated to amateur radio operators around the world. The call signs are used to legally identify the station or operator, with some countries requiring the station call sign to always be used and others allowing the operator call sign instead.
Call signs in Canada are official identifiers issued to the country's radio and television stations. Assignments for broadcasting stations are made by the Canadian Radio-television and Telecommunications Commission (CRTC), while amateur stations receive their call signs from Innovation, Science and Economic Development Canada. Conventional radio and television broadcasting stations assignments are generally three, four or five letters long and almost exclusively use "C" call signs; with a few exceptions noted below, the "V" calls are restricted to specialized uses such as amateur radio.
Call signs in the United States are identifiers assigned to radio and television stations, which are issued by the Federal Communications Commission (FCC) and, in the case of most government stations, the National Telecommunications and Information Administration (NTIA). They consist of from 3 to 9 letters and digits, with their composition determined by a station's service category. By international agreement, all call signs starting with the letters K, N and W, as well as AAA-ALZ, are reserved exclusively for use in the United States.
Maritime call signs are call signs assigned as unique identifiers to ships and boats. All radio transmissions must be individually identified by the call sign. Merchant and naval vessels are assigned call signs by their national licensing authorities.
A ship identifier refers to one of several types of identifiers used for maritime vessels. An identifier may be a proper noun ; a proper noun combined with a standardized prefix based on the type of ship ; a serial code; a unique, alphanumeric ID ; or an alphanumeric ID displayed in international signal flags. Some identifiers are permanent for a ship while others may be changed at the owners' discretion although regulatory agencies will need to approve the change. Modern ships will usually have several identifiers.
