

It became a worldwide standard when it was included in the service regulations of the first International Radiotelegraph Convention signed on 3 November 1906, which became effective on 1 July 1908. SOS originated in German government maritime radio regulations adopted effective 1 April 1905. The phrase "SOS" used on a Belgian emergency telephone traffic sign Moreover, due to its high-profile use in emergencies, the phrase "SOS" has entered general usage to informally indicate a crisis or the need for action. Later in popular usage it became associated with mnemonic phrases such as "Save Our Souls" and "Save Our Ship".

SOS, when it was first agreed upon by the International Radio Telegraphic Convention in 1906, was merely a distinctive Morse code sequence and was initially not an abbreviation. ( IWB, VZE, 3B, and V7 form equivalent sequences, but traditionally SOS is the easiest to remember.) 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. 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. SOS is a Morse code distress signal ( ▄ ▄ ▄ ▄▄▄ ▄▄▄ ▄▄▄ ▄ ▄ ▄ ), used internationally, that was originally established for maritime use. Problems playing this file? See media help.
