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See media help. The International Radiotelephony Spelling Alphabet or simply Radiotelephony Spelling Alphabet, commonly known as the NATO phonetic alphabet, is the most widely used set of clear-code words for communicating the letters of the Roman alphabet. Technically a radiotelephonic spelling alphabet, it goes by various names, including ...
Nihilist cipher. In the history of cryptography, the Nihilist cipher is a manually operated symmetric encryption cipher, originally used by Russian Nihilists in the 1880s to organize terrorism against the tsarist regime. The term is sometimes extended to several improved algorithms used much later for communication by the First Chief ...
Worldwide distribution of country calling codes. Regions are coloured by first digit. Country calling codes, country dial-in codes, international subscriber dialing (ISD) codes, or most commonly, telephone country codes are telephone number prefixes for reaching telephone subscribers in foreign countries or areas via international telecommunication networks.
The use of alphanumeric codes for exchanges was abandoned in Europe when international direct dialing was introduced in the 1960s, because, for example, dialing VIC 8900 on a Danish telephone would result in a different number to dialling it on a British telephone. At the same time letters were no longer placed on the dials of new telephones.
Telephone numbers listed in 1920 in New York City having three-letter exchange prefixes. In the United States, the most-populous cities, such as New York City, Philadelphia, Boston, and Chicago, initially implemented dial service with telephone numbers consisting of three letters and four digits (3L-4N) according to a system developed by W. G. Blauvelt of AT&T in 1917. [1]
Morse code. Morse code is a telecommunications method which encodes text characters as standardized sequences of two different signal durations, called dots and dashes, or dits and dahs. [3] [4] Morse code is named after Samuel Morse, one of the early developers of the system adopted for electrical telegraphy .
It is common to write phone numbers as (0xx) yyyyyyy, where xx is the area code. The 0 prefix is for trunk (long-distance) dialing from within the country. International callers should dial +92 xx yyyyyyyy. All mobile phone codes have four digits, and start with 03xx. All mobile numbers have seven digits, and denote the mobile provider on a ...
The QR code system was invented in 1994, at the Denso Wave automotive products company, in Japan. [5] [6] [7] The initial alternating-square design presented by the team of researchers, headed by Masahiro Hara, was influenced by the black counters and the white counters played on a Go board; [8] the pattern of position detection was found and determined by applying the least-used ratio (1:1:3 ...