SOS is the international
Morse code distress signal (
· · · – – – · · ·). This distress signal was first adopted by the
German government in
radio regulations effective April 1, 1905, and became the worldwide standard under the second International Radiotelegraphic Convention, which was signed on November 3, 1906, and became effective on July 1, 1908. SOS remained the maritime radio distress signal until 1999, when it was replaced by the
Global Maritime Distress and Safety System. SOS is still recognized as a visual distress signal.