In 1872, it was decreed by maritime
regulatory organizations that each ship should identify itself with four
letters in the English alphabet. Thus it
was a simple matter for the flagmen on each ship to spell out the ship’s identification with four alphabet
flags, rather than spelling out in full the long name of the ship in flag
language.
When wireless stations began to
proliferate right at the end of the 1800s, each wireless station adopted its
own callsign, generally made up of two letters.
For example, CC Cape Cod, PH San
Francisco.
The signing of protocols at the
Second Wireless Telegraphy Convention in Berlin took place on November 3, 1906
and these documents required that ship callsigns should consist of a group of
three letters.
In 1908, the Marconi company in
England required that all Marconi wireless stations on land and at sea should
begin with the letter M followed by two additional letters for local
identification. For example, MCC Cape Cod, MGY the SS Titanic.
On June 4, 1912 the papers were
signed at the International Telegraphic Conference in London and one of the
protocols was that each country throughout the world was allocated a cluster of
letters in the English alphabet with which to identify their respective
wireless stations. For example, wireless
callsigns in Great Britain would begin with the letter B or G or M, and
callsigns in France with the letter F, and American callsigns could begin with
N or W, or with K beginning at KDA.
On May 9, 1913, the United States
implemented its own system of callsigns (ultimately within the framework of its
own internationally allocated alphabetic letters). The country was divided into nine wireless
districts and thus local coverage stations were granted callsigns that
comprised a number followed by two letters.
Examples: 2XG New York, 3XZ Washington DC.
An international designator was
added subsequently and the number of letters after the number was increased to
three. Examples: W2XAD Schenectady NY,
W9XAA Chicago. The X in these callsigns
indicated experimental. Four letter
callsigns for mediumwave stations were introduced in 1920 (KDKA), and similar
four letter callsigns for shortwave were introduced in 1939 (KGEI, WRUL).
Soon after the end of World War 1,
medium wave stations began to proliferate worldwide. Within continental Europe for example,
Germany was granted the prefix number 4, Switzerland was granted 9, and Great
Britain was granted 2 5 and 6 as the initial numbers for their callsigns. However, there seems to be no categorized
cluster for the use of 2 5 and 6 in Great Britain, not in chronological order
nor in geographic order.
Australia followed a similar
pattern, and each state was granted a prefix number, followed by two letters
for the station identification, such as for example: 2GB Sydney New South
Wales, 5DN Adelaide South Australia, 7NT Northern Tasmania, 9PA Port Moresby
Papua New Guinea.